There is confusion over the whereabouts of Guinea-Bissau's Prime Minister, Carlos Gomes Junior, after soldiers launched an apparent coup.
Earlier reports said Mr Gomes had been arrested by the army, but diplomats told the BBC they believe he is safe somewhere in the capital, Bissau.
Soldiers have been seen outside several embassies, apparently searching for Mr Gomes, who is running for president.
Meanwhile, the UN Security Council has strongly condemned Thursday's revolt.
A statement firmly denounced the "incursion by the military into politics" and called on the army rebels to ensure the safety of Mr Gomes, interim President Raimundo Pereira, and all senior officials currently detained.
In Bissau, a communique issued by the "military command" - as the rebel troops have named themselves - said its forces had detained the head of the armed forces, Antonio Indjai.
Earlier on Friday, a military press attache, Francelino Cunha, told the Associated Press that Prime Minister Gomes had been arrested inside his home - the scene of heavy gunfire and military activity on Thursday night.
The UN statement said the members of the Security Council "urge all parties to exercise maximum restraint, refrain from violence and remain calm."
"[They] note with profound regret that these events are occurring just prior to the launch of the campaign for the second round of the presidential election."
The suspected coup has also been denounced by the West African regional grouping, Ecowas, which said the military had once more demonstrated its "penchant to maintain Guinea-Bissau as a failed state".
Ecowas recently intervened in Mali, where there was a coup last month, ordering the coup leader to hand over power after imposing sanctions.
Diplomatic sources quoted by the BBC's Thomas Fessy said Prime Minister Gomes was safe somewhere in Bissau.
Although the situation was calm on Friday, soldiers could be seen around several embassies, suggesting that they were searching for the man who was well on course to become president after this month's run-off vote, our correspondent adds.
There were unconfirmed reports that Mr Pereira, the interim president, was also being held, with one of his bodyguards telling the AFP news agency that he had been arrested on Thursday by a group of soldiers.
Army spokesman Daba Na Walna later told reporters: "The prime minister and interim president are doing well. I can't tell you any more."
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.
Our correspondent says questions remain over who is behind this operation claimed by an unknown "military command", which does not seem to include the army's top brass.
In a statement read on state radio on Friday morning, members of the "military command" said they had "no ambition for power" and had acted to halt what they called "foreign intervention".
They 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 had 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 March's first round, 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.
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