Soldiers in Gabon burst into state radio offices early on Monday and called on the people to "rise up", in an apparent coup attempt as ailing President Ali Bongo is out of the country.

Shots were heard the around state television headquarters in Libreville, capital of the oil-rich West African nation, at about the same time as the message was read at 6.30am.

Military vehicles blocked access to the boulevard where the offices are located, an AFP correspondent said.

The dramatic developments came as Bongo is recovering at a private residence in the Moroccan capital Rabat after suffering a stroke.

A message was read on state radio by a person who identified himself as Lieutenant Ondo Obiang Kelly, the deputy commander of the Republican Guard and head of a previously unknown group, the Patriotic Youth Movement of the Gabonese Defence and Security Forces (MPJFDS).

He announced a "national restoration council" would be formed.

The movement "calls on all young people from forces for the defence and security and Gabonese young people to join us", the officer said.

Three soldiers wearing the green beret of the Republican Guard were visible on a video of the speech circulating on social media and authenticated by AFP.

"We cannot abandon our homeland," the officer said.

"The eagerly awaited day has arrived when the army has decided to put itself on the side of the people in order to save Gabon from chaos.

"If you are eating, stop; if you are having a drink, stop; if you are sleeping, wake up. Wake up your neighbours... rise up as one and take control of the street," he said.

'A difficult period'

The officer called on the people of Gabon to occupy public buildings and airports throughout the country.

The 59-year-old Bongo has not been back to Gabon since he fell ill in Saudi Arabia on Oct 24. It was revealed last month that he had suffered a stroke.

In his absence, the Constitutional Court transferred part of the powers of the president to the prime minister and the vice president.

On Dec 31, Bongo addressed the country for the first time since falling ill, saying in a recorded speech from Morocco that he had "been through a difficult period".

The MPJFDS considers the speech "shameful" for a "country (which) has lost its dignity", the officer said in the speech on state delivered on Monday.

The Bongo family has governed the equatorial African nation for five decades.

Ali Bongo was elected head of state after his father's death in 2009.

He was narrowly re-elected in 2016 following a presidential poll marred by deadly violence and allegations of fraud.