SANAA: Suspected Al-Qaeda gunmen on a motorbike have shot dead a high-ranking security official in Yemen's Dhammar province, south of Sanaa, the official Saba news agency reported on Thursday.

"Two gunmen on a motorbike opened gunfire on Colonel (Abdullah) al-Mushki killing him immediately," Saba quoted a security official in Dhammar as saying about Wednesday's shooting.

"Security services are carrying out vast investigations to hunt down the criminals behind this crime which carries the fingerprints of Al-Qaeda," said Saba.

Such hit-and-run shootings have killed dozens of security officers last year, prompting authorities early in January to impound illegal motorbikes.

The interior ministry said that 40 members of the security forces and four civilians were killed in 2012 in hit-and-run shootings by gunmen on motorbikes.

There are over 200,000 motorbikes across Yemen, most of which are unregistered, according to Sanaa police.

Al-Qaeda in the Arabian Peninsula, blamed for most of the killings, has not claimed responsibility for any of the assassinations.

AQAP took advantage of the weakness of Yemen's central government during an uprising in 2011 against now ousted president Ali Abdullah Saleh, seizing large swathes of territory across the south.

But a month-long government offensive that ended in June pushed most of the militants to the more lawless desert regions of the east.