Cameroon on Thursday described as "biased" comments by UN experts claiming the main opposition leader Maurice Kamto was under house arrest, and accusing Yaounde of "excessive force" in recent demonstrations.
Kamto is the chief opponent of President Biya, who has ruled the Central African country for 38 years. His house has been surrounded by police for 24 days.
The opposition politician told AFP on Tuesday by phone that he was still being prevented from leaving and was "sequestered", without any notification from the authorities.
A court hearing which was to rule on a complaint by Kamto's lawyers for "administrative assault" has been postponed until October 20, an AFP journalist learned on Thursday.
UN rights experts on Monday called for Kamto's release from house arrest for calling for peaceful protests against Biya. They also called for the release of dozens of others reportedly arrested during demonstrations on September 22.
In a statement received on Thursday by AFP, the government called the UN experts' comments "subjective and biased" and accused them of having relaying and amplifying "untruths".
It alleged that Kamto and his associates had defied laws and regulations by "violating the ban on public demonstration".
"Faced with such threats to public order, it was naturally incumbent on the public authorities to take the necessary measures to deal with the situation, which has been done," the statement said, without elaborating.
Of 294 arrested supporters of the Movement for the Rebirth of Cameroon (MRC) led by Kamto, it added that 176 had been released.
"Nine people... formally identified as being leaders, planners or organiser of insurrectional marches are currently in the hands of justice," the statement said.
Some 109 people were also brought before courts in the economic capital Douala and western Bafoussam.
Kamto officially lost to Biya in 2018's presidential election, and was arrested in January last year following a march protesting the vote. Biya ordered him freed nine months later under international pressure.
On September 18 of this year he called for mass protests to demand electoral reforms as well as a ceasefire in the country's insurgency-hit English-speaking areas.
Four days later, police crushed a demonstration in the country's economic capital Douala, detaining 93 protesters of whom 58 were still in custody as of Tuesday, according to their lawyers. They were among more than 500 people arrested across the country.