The suspected mastermind of last week's twin suicide bombings in Tunis was killed in an overnight firefight with police outside the capital, the interior ministry said Wednesday.

A policeman was also killed in the exchange in the working class suburb of Intilaka, ministry spokesman Sofiene Zaag told AFP.

"The terrorist Aymen Smiri was implicated in the twin suicide bombings on Thursday and investigations proved that he was the mastermind of the operation," Zaag said, adding he was a "very active and very dangerous leader."