Inmates at the Bauchi prison have set it on fire and an unknown number of inmates have again escaped from the prison where some members of the Boko Haram sect were being held.

Armed police and fire fighters were sent in to control the unrest at the prison in the city of Bauchi, where heavily armed gunmen believed to be members of the Boko Haram sect freed close to 800 inmates in early September.

Bauchi state government officials said the riot at the prison, which holds Boko Haram members arrested during last year's trouble, was triggered by a dispute over an amnesty granted to some inmates, including two sect members.

"It was a protest by some of the prisoners who heard that the governor had granted amnesty to a few of them,"
Abdulmuminu Mohammed Kundak, an adviser to the state governor, said on Friday. "They should know that it is not every prisoner that will be released at the same time."

Boko Haram members said in a radio interview broadcast in the local Hausa language in Maiduguri last month that they were behind recent shootings and warned they would kill more police, traditional rulers and politicians.

Security has been tightened in recent months in Maiduguri, with the police and army carrying out joint patrols and a dusk-to-dawn ban on motorcycles, used in some shootings.