SANAA, November 5 (IslamOnline & News Agencies) - The United States has taken the anti-terror fight in Yemen into its own hands, killing an alleged Al-Qaeda operative and five associates in an attack attributed to the CIA, while Sana'a says it is still investigating the incident.

According to U.S. media, it was a missile fired by a drone operated by the U.S. Central Intelligence Agency (CIA) which killed the six Al-Qaeda suspects Sunday, November 3 afternoon in the desert region of Al-Naqab in Ma'rib province, 200 kilometers (125 miles) east of Sana'a, Agence France-Presse (AFP) reported.

CNN television, citing unnamed sources, reported that the suspects' vehicle was hit by a Hellfire missile fired from the CIA drone.

NBC News said the car had been observed by the pilot-less plane for a period of time before it was attacked.

Secondary explosions were seen after the missile hit the vehicle, indicating there were explosives inside the car, it said.

Yemeni authorities have said the six people were killed when the vehicle they were traveling in was destroyed by a powerful explosion.

The alleged main Al-Qaeda operative killed in the blast was identified as Ali Qaed Sunian al-Harithi, also known as Abu-Ali. A U.S. defense official claimed that Harithi was "one of the kingpins" in the October 2000 bombing of the USS Cole in the south Yemeni port of Aden that claimed the lives of 17 American sailors.

The CIA refused to comment on reports that it had killed the six. U.S. Defense Secretary Donald Rumsfeld said Harithi was thought to have been allegedly involved in the Cole attack.

"Needless to say he is an individual who has been sought after as an Al-Qaeda member as well as a suspected terrorist connected to the USS Cole. So it would be a very good thing if he were out of business," he said.

But Rumsfeld declined to comment when asked if the United States played any role in Harithi's death, saying the reports he had received were incomplete.

U.S. ambassador in Yemen Edmund Hull was in Marib on the day of the incident and did not leave the area until Monday, November 4, local tribal notables told AFP Tuesday, November 5.

"U.S. military experts were seen in the region with Yemeni special forces in recent days," said one tribal dignitary, requesting anonymity.

Witnesses told AFP Monday the explosion was caused by two missiles fired from a military helicopter.

A Yemeni interior ministry spokesman said Monday that security services were "continuing to investigate the circumstances of the incident and determine the identities of the car's occupants."

"According to initial indications, Ali Qaed Sunian al-Harithi, who was sought by security services for taking part in acts of sabotage, was among the six killed," the spokesman said.

The interior ministry on Monday also announced the arrest of two suspects in a separate incident the previous day in which gunmen opened fire at a helicopter belonging to U.S. oil firm Hunt Oil Co. shortly after its takeoff from Sana'a airport, injuring one American.

Preliminary investigations point to a "terrorist" attack, a source close to the inquiry into that incident told AFP.

In the wake of the anti-U.S. terror attacks of September 11, 2001, blamed on Al-Qaeda, Sana'a launched, at Washington's behest, a crackdown on suspected members of the terror network.

U.S. military personnel have also been deployed in Yemen to help Sana'a combat the militants, though Sana'a has insisted that they would only be involved in training and intelligence, and not in operations.