A bomb destroyed the secret police headquarters in Aden on Saturday, residents of the southern Yemen city said, in an attack that one official blamed on Al-Qaeda.

The four-storey building in the Tawahi neighbourhood of Aden was razed by the blast which occurred at around 6 am (0300 GMT) and which could be heard across the city, residents said.

One local official, who declined to be named, said the bombing was carried out by Al-Qaeda in the Arabian Peninsula (AQAP).

"These elements have since (the start of) August destroyed or removed secret police files in Aden," the official said.

He alleged that AQAP militants entered Yemen's second city just weeks after it was retaken from Iran-backed rebels in mid-July.

The explosion caused no casualties, the official said, adding that AQAP members had withdrawn from the area after the blast.

AQAP, which the United States says is the global extremist network's most dangerous branch, has taken advantage of months of violence and chaos in Yemen to make territorial gains, overrunning in April the port of Mukalla, capital of the eastern Hadramawt province.