Nine people suspected of links with gunmen behind the attack on a museum in Tunis that left 21 dead have been arrested, the presidency said Thursday.

"The security forces were able to arrest four people directly linked to the (terrorist) operation and five suspected of having ties to the cell," a presidency statement said without giving further details.

Twenty foreign tourists were among those killed in the attack Wednesday on the national museum. There has been no claim of responsibility. (AP)