Senior security officials have reportedly been detained in the Ivory Coast commercial capital, Abidjan, as part of a crackdown following an alleged coup plot.
Rebels say they remain committed to peace
The plot has threatened the future of a shaky power-sharing agreement supposed to end last year's civil war.
But tension is high and armoured vehicles are patrolling the streets, while the police have increased identity checks.
Meanwhile, France says it has arrested the suspected killers of two of their peacekeeping troops, who died on Monday.
The former colonial power has some 4,000 troops in Ivory Coast monitoring the peace deal, which it helped broker.
On Thursday, General Abdoulaye Coulibaly, a former member of the military junta which seized power in 1999, was arrested after he flew into Abidjan from Paris.
He is not related to the leader of the 1999 coup, Ibrahim Coulibaly, who was arrested in Paris last weekend and is accused of being the mastermind of the alleged coup plot.
The authorities refuse to comment on the wave of arrests in Abidjan, which are reported to include members of the presidential guard.
The Ivorian Movement for Human Rights (MIDH) said it had received reports of about 100 arrests but has not been able to verify all the reports.
The former rebels accused France of acting as a "puppet" of Mr Gbagbo after detaining 11 people last week.
"No one is stupid, and proof exists that the supposed mercenaries are working for the Ivorian presidency," said a statement from the former MPCI rebels.
In another sign of how tense relations are between the different parts of the power-sharing government, the chairman of Mr Gbagbo's FPI party, Affi N'Guessan, accused Prime Minister Seydou Diarra of being behind the alleged plot.
The country remains divided between a rebel-held north and the south, controlled by Mr Gbagbo.
The division also has a religious and ethnic dimension, with Mr Gbagbo getting most of his support from Christians and animists.
Affi N'Guessan (l) accused Seydou Diarra (r)
Mr Diarra, General Coulibaly, Mr Coulibaly and most of the former rebels are northern Muslims.
During the conflict, many Muslims, including immigrants from Ivory Coast's neighbours were harassed and even killed after being accused of backing the rebels.
Prime Minister Seydou Diarra recently said his six-month-old administration had reached a "deadlock" as Mr Gbagbo's government and the former rebels have been unable to agree on who should control the defence and security ministries.
Charles Ble Goude, the leader of a radical pro-Gbagbo student group which orchestrated massive street protests in January, also accused Mr Diarra of being a rebel and called on him to resign, or pledge loyalty to the president.
"You are a hypocritical rebel who has been exposed," he wrote in the daily Le National.
French investigators say that those arrested have admitted to plotting to assassinate Mr Gbagbo.
However, a lawyer for Ibrahim Coulibaly says he denies the charges.
Those detained in France are from France, Ivory Coast and Lebanon.