Soldiers in Guinea-Bissau have arrested the outgoing Prime Minister, Carlos Gomes Junior, in a suspected coup bid.
A military press attache and his wife confirmed his detention, after gunfire was heard in the capital overnight.
The country's interim President, Raimundo Pereira, is also being held, according to the AFP news agency.
Correspondents say Mr Gomes, who is running for president in this month's run-off vote, is unpopular with the military over plans to scale it down.
Guinea-Bissau, an impoverished former Portuguese colony, has been plagued by a long series of coups since gaining independence in 1974 - and has recently become an important staging post for gangs smuggling drugs from Latin America to Europe.
'No ambition for power'
Military press attache Francelino Cunha told the Associated Press that Mr Gomes had been arrested in his home - the scene of heavy gunfire and military activity on Thursday evening.
Mr Pereira's bodyguard told AFP that the president had also been arrested on Thursday by a group of soldiers.
In a statement read on state radio on Friday morning, the military said it had "no ambition for power" and had acted to halt what it called foreign intervention.
It alleged the interim government had done a secret deal to allow Angolan troops to wipe out Guinea-Bissau's army.
Earlier this week Angola said it was withdrawing about 200 Angolan officers who have been in the country for the last year to help with training and army reforms.
Last month's emergency election was called after the death in January of President Malam Bacai Sanha, following a long illness.
The second-placed candidate in the March election, former President Kumba Yala, has said he will boycott the run-off vote scheduled for 29 April. He alleged that the election had been fraudulent.
The West African regional organisation Ecowas said it would not tolerate the actions of the military.
It recently intervened in Mali, where there was a coup last month, ordering the coup leader to hand over power after imposing sanctions.
In a statement, the African Union's commission chief Jean Ping said the army's "outrageous acts which undermine the efforts to stabilise the situation in Guinea-Bissau and tarnish the image of the country and Africa," AFP reports.