Dozens of soldiers are reported to have been arrested and detained in several locations in Guinea's capital, Conakry.
Lansana Conte is seeking another term in December
The arrests come three weeks ahead of a presidential election which has been boycotted by the opposition alliance.
Several military sources have described the action as "routine", but the BBC's Alhassan Sillah says this explanation is completely inadequate.
Earlier this month, President Lansana Conte declared that some soldiers were planning a coup d'etat.
Among the officers arrested is Lieutenant Alpha Ousmane Diallo, son of a former controversial speaker of parliament , El hadj Bubacarr Biro Diallo.
His wife Kadiatou, described how some military men came for her husband on Wednesday night saying he was urgently needed by his boss.
"I have not seen him since," she told our reporter.
Several spouses of arrested men have been complaining bitterly saying they do not know where their partners have been taken to.
Our reporter says the arrests are bound to increase opposition fears ahead of the 21 December vote.
In 2001, Mr Conte - who seized power in the ex-French colony in 1984 - won a referendum to change the constitution so he could run for a third term.
The only challenger to Mr Conte is Mamadou Bhoye Barry, of the Union for National Progress party, who is barely known - even among Guineans.
The European Union is refusing to finance or send election observers because of doubts over the conduct of the poll.
The main opposition parties have warned of civil unrest and the danger of the country slipping into the kind of conflicts seen in neighbouring countries like Liberia and Ivory Coast.