CEUTA/MADRID, Oct 19 - When heavily pregnant Fatna and her disabled son arrived in Spain's North African enclave of Ceuta during a chaotic mass border crossing on July 30, she hoped to be high on authorities' list for help.

Nearly three months later, with her newborn baby girl suffering from kidney problems, Fatna, 21, and her family urgently need to reach mainland Spain for specialist hospital treatment.

However, travelling while her asylum claim is under review requires a permit that Spain's socialist government – ordinarily a staunch advocate of immigration – has been reluctant to grant to any of the thousands of migrants remaining in Ceuta.

Some are still scattered on the streets or hiding in the rolling hills of the tiny 20-sq-km port city on Morocco's northeast border.

Prime Minister Pedro Sanchez's government is under pressure from the EU and an increasingly frustrated populace to sort out the crisis and faces a snap election on November 29.

It is working on shortcuts for asylum applications with the intention of sending most people home, mainly to Morocco, on the basis of being economic migrants not real asylum-seekers. That, NGOs fear, risks violating migrants' rights.

Sanchez, one of Europe's few remaining left-leaning leaders, said this week that Spain was managing the flood of cases "responsibly, with a sense of solidarity and respecting migrants' human rights".

But more than 20 interviews by Reuters with migrants, lawyers, NGOs, and security forces revealed that many of those who remain have clear grounds for asylum or humanitarian protection: from unaccompanied minors to LGBT Moroccans fearing imprisonment if deported and families like Fatna's classified as vulnerable under EU law.

Last week, eight charities including Oxfam and Amnesty International filed a complaint with Spain's ombudsman seen by Reuters alleging "grave rights violations" in the tiny Ceuta enclave. They included the forced return of migrants from conflict-hit countries and denial of interpreters and legal assistance.

Spokespeople for Spain's central government, interior ministry, territorial policy ministry and migration ministry did not respond to Reuters requests for comment on the mistreatment accusations.

"There are people who will truly be in enormous danger if they are returned to Morocco," said Wendell Soares, coordinator of the Catholic migrant reception centre San Antonio which has taken in Fatna's family and dozens more vulnerable people, far beyond its usual capacity of seven.

"When the word ‘immigrant’ is used, it creates a collective image, as if they were all the same. Every person has their own story." DEPORTED WITHOUT EXPLANATION Spanish right-wing and far-right parties were already angry with Sanchez's government for providing legal status to nearly 1 million irregular migrants earlier this year. They have cast July's crossing as a deliberate invasion by Morocco – an accusation Morocco denies – and demanded that all migrants be returned.

But despite plans for a new EU-wide procedure enabling accelerated deportations in future emergency scenarios, current rules require that migrants be assessed case-by-case.

While most are from Morocco, the government estimated in August that more than 1,000 of the migrants remaining were from sub-Saharan countries whose nationals are granted asylum in over 90% of cases in Spain, according to government statistics.

The EU's new pact requires that cases be processed in border zones to permit faster deportations. But it does not require applicants to stay where they arrived, allowing for transfers to other border zones in Spain that would alleviate pressure on the 84,000-person enclave of Ceuta, Europe's only land border with Africa.

If vulnerable migrants' cases are to be properly assessed, such transfers are the "only option", said Juan Miguel Morales, director-general of NGO Sur Acoge.

While 262 minors have been transferred to the Spanish mainland since the July crossing, the government's strategy for the remaining adults has been to convince as many as possible to return of their own volition. The government said this week that 12,000 had chosen to cross back since mid-August.

"There are no covert deportations under any circumstances," Interior Minister Fernando Grande-Marlaska said, describing the returns as voluntary and adding that up to 1,200 asylum applications had been received and 700 of them resolved.

However, at least nine NGOs have in public communication or interviews with Reuters claimed that migrants they support were coerced to return.

Asociación Elin said migrants from Sudan and Chad were summoned by police on September 24 and 25 and deported without warning, according to the complaint to the ombudsman.

In text messages reviewed by Reuters, Moroccan migrant Azhaar Chaouni told volunteers at German NGO Mission Lifeline that he and other migrants faced the same fate, after being picked up in buses by police from their makeshift camps on the beach and told they were being taken to reception centres.

"They deported us without explanation," Chaouni wrote, saying he was in Morocco.

Morocco's designation as a "safe country of origin" under EU rules does not strip its citizens of the right to apply for asylum, said Andrea de Petris, immigration expert at Brussels-based think tank CEPN.

"Each individual must be guaranteed a specific assessment of their personal circumstances," added De Petris who estimates the procedure would inevitably be "lengthy and costly".

Stories of others disappearing have instilled fear in Rayane, a 19-year-old gay Moroccan awaiting news on his asylum application in the San Antonio reception centre. Rejected by his family and unable to live openly in Morocco where same-sex sexual acts are prosecuted, he is desperate to get to mainland Europe.

"I can’t even imagine myself going back to Morocco. I’d kill myself before even crossing the border," he said.

PACT EXPOSED Frontline workers and NGOs on the ground say the situation in Ceuta has proven that the 12-week limit set in the EU’s migrant pact for processing asylum applications is unrealistic, with seven stating they expect the process to drag on for months.

A lack of resources from staff to functioning computers meant that only around 100 migrants' cases were being registered daily by October 14, according to police union representative Raul Piera.

The union estimates roughly 7,000-8,000 more migrants are still scattered across the city, sleeping rough or squeezed into facilities provided by charities and civil society groups filling the gap left by Ceuta's overwhelmed social services. "Looking at the remaining workload, this will last well into next summer," said Piera.

Spain's government has declined to comment on estimates of unregistered migrants, with Territorial Policy Minister Angel Victor Torres telling reporters on October 14 that it was impossible to know how many were hiding.

Doctors in Ceuta's only hospital are treating migrants for scabies, tuberculosis and gastrointestinal infections caused by long periods outdoors, said Enrique Robiralta, head of the doctors' union. At least seven women have given birth.

Fatna and her husband Mohamed are desperate to stay in Spain, fearing for the new baby and convinced their 3-year-old disabled son will die in Morocco. "We are doing everything for our son," said Mohamed.