The Foreign Office confirmed that Mark Rothermel, an aid worker from Essex, had been linked to the break-out, in the Mikalou district of the city.
Details of the allegations against the man are not known, but according to a report - which the Foreign Office would not confirm last night - he had been arrested on suspicion of spying.
The Congolese Observatory of Human Rights said it had visited Mr Rothermel during his detention.
The Foreign Office spokesman said yesterday: "We can confirm that a British man was involved in the escape when Brazzaville prison came under mob attack. The man, who has contacted the British honorary consul in Brazzaville, was detained without charge on 6 November."
The break-out reportedly happened on Wednesday as panic ensued when police officers tried to disarm a soldier at the prison, who was killed in the exchange. Congolese soldiers have been banned from carrying weapons in certain parts of Brazzaville since street battles and looting broke out in December.
Prisoners are being held in police cells because Brazzaville's prison was destroyed in the 1997 civil war.
The Congo Republic borders on the huge Democratic Republic of Congo across the Congo river, which is embroiled in a civil war over control of its mineral-rich territory.
The Congo Republic government, which has barred a United Nations investigation into alleged massacres by its own troops, yesterday called for an investigation into the reported massacre of 500 civilians by rebel forces.
Congo's UN ambassador, Andre Mwanga Kapanga, also urged the Security Council to call on the Ugandan and Rwandan troops he accused in the slaughter to stop all atrocities and leave the country.
An Italian missionary news agency reported that rebel forces led by a Rwandan commander hunted down and slaughtered 500 civilians in the village of Makobola, 10 milessouth of the Lake Tanganyika port of Uvira, between 30 December and 1 January.
The attack was in apparent retaliation for the killing of rebel soldiers by a force known as the Mai-Mai.Reuse content