Namibia's Petroleum Amendment Bill cleared its second reading in parliament late on Tuesday, a week after opposition lawmakers walked out of the debate over its current form.

The law has sparked fierce debate among the public, opposition parties and analysts over concerns it strips away key oversight functions and concentrates power over Namibia's energy sector in the hands of the presidency.

It is seen as a major test for President Netumbo Nandi-Ndaitwah, who has championed it as a cornerstone of her regulatory reform agenda since taking office.

The presidency has dismissed concerns over the bill, which will establish a new regulatory authority in the office of the president, saying it will facilitate quicker decision-making and has the necessary checks and balances.

The bill will now be referred to parliamentary committees for a clause-by-clause review before returning to the National Assembly for final approval.

Namibia, a global exploration hotspot, is pushing for its first oil production around 2030.

"The decision to create a mini ministry of mines and energy in the presidency is a wrong move and undemocratic," Immanuel Nashinge, parliamentary leader of the official opposition Independent Patriots for Change, told Reuters after his party helped lead last week's walkout.

Lawmakers have also criticised the procedural handling of the bill, pointing out that upstream leadership structures have been operating ahead of formal legislative backing.

The ruling party holds a slim majority in the National Assembly with 51 out of 96 seats and is riven by internal factions ahead of their elective conference next year, making smooth passage of the bill unclear, analysts said.

"Namibia's oil future must be built on transparency, accountability and strong institutions, not political control and rushed decisions," Ndumba Kamwanyah, an independent political analyst, said.