Yemeni security forces have arrested six suspected members of Al-Qaeda, including a mosque's imam, in the southern city of Aden, a security official said Friday.

Police raided a house in the Kraitar neighbourhood of Aden at dawn on Friday and arrested three suspects, the official said, adding that the imam of a mosque in Mansura area was also arrested from his house late on Thursday.

Two others were arrested on Thursday following a raid on a house in the neighbourhood of Dar Saad, the official added, requesting anonymity.Security forces have been on heightened alert in Aden following an attack by suspected Al-Qaeda militants Saturday on intelligence headquarters that killed 19 soldiers.

Police have set up at least six new checkpoints in the city, an AFP correspondent reported.Al-Qaeda's branch in Yemen exploited the decline in central government control last year that accompanied Arab Spring-inspired protests that eventually forced president Ali Abdullah Saleh to cede power in February.

Militants linked to Al-Qaeda had seized control of Zinjibar, Jaar, Shuqra and other towns across the southern province of Abyan, but government forces in May launched an all-out offensive and recaptured the towns the following month.