A senior Yemeni intelligence officer was shot dead in the capital, Sanaa, when a speeding gunman on a motorcycle opened fire Tuesday, the latest episode in an assassination campaign aimed at security officials as government forces wage a crackdown on al-Qaida suspects.

Al-Qaida in Yemen has carried out a string of assassinations of top security and military officials and deadly suicide bombings in recent months, raising concerns that al-Qaida militants are bouncing back and getting bolder after suffering defeats this year in a U.S.-Yemeni military offensive.

Security officials said they believe the group has a hit list to kill more from their ranks in an attempt to paralyze Yemen's new leadership and throw the anti-al-Qaida assaults into turmoil.

One official said the attacker on a motorcycle killed Gen. Khaled al-Hashim on the spot and fled the scene. He said Al-Hashim was one of a number of Iraqi military experts hired by Yemen after the fall of Saddam Hussein in 2003.

The attack follows a similar drive-by shooting last week that killed a top Yemeni security official who worked at the U.S. Embassy in Sanaa. Qassem Aqlani was on his way to work when a masked gunman on a motorcycle opened fire on him and fled the scene on Thursday, officials said.

That attack, which carried the hallmarks of an al-Qaida operation, was near Aqlani's home in western Sanaa, while the embassy is located in the eastern part of the capital. Aqlani, who was in his 50s, had been working for the embassy for 11 years, the U.S. State Department said.

Elsewhere, in the country's southern Abyan province, security officials said a suicide bomber attacked a checkpoint manned by a pro-government militia outside the town of Mudya, killing six from the group that has participated in the offensive against al-Qaida.

Mudya resident Khaled al-Fayadi said the checkpoint was attacked by armed men, followed by an explosives-laden car that approached five minutes later and blew up.

Security officials say the six killed in the attack are all militiamen, part of so-called Popular Committees that were formed to fight alongside the military to oust al-Qaida from their towns and villages.