WASHINGTON, Jan 1 The CIA base in Afghanistan that was attacked by a suicide bomber on Wednesday played a central role in drone attacks along the Pak-Afghan border, the US media reported on Friday.

Seven CIA agents were killed in a suicide attack on Wednesday at the base near Khost. The chief of the Forward Operating Base Chapman was among those killed while six others were injured. As is customary, the CIA declined to identify the victims.

The deaths marked the largest single-day loss for the spy agency since the Beirut embassy bombing in 1983.

CNN reported that two of those killed were contractors for the security firm Xe, formerly known as Blackwater.

The base chose targets for strikes by remote-controlled drones and The Washington Post noted the attack caused “a devastating blow” to one of the agency's key intelligence hubs for counterterrorism operations.

Yet the CIA continued the drone strikes. On Friday, missiles from a US drone slammed into a car in North Waziristan, following another strike on Thursday.

A CIA official told the Post that the attack on their base would only increase the agency's resolve to continue the airstrikes.

The New York Times noted that the base at Khost showed the agency's increasing involvement in paramilitary operations, including missile strikes in Pakistan and counterterrorism operations in Yemen.

As a result, the CIA faces greater risks than ever, and Wednesday's attack, underlined that risk, the report added.

The Post reported that US personnel at the site of the attack were heavily involved in the selection of Al Qaeda and Taliban targets for drone aircraft strikes. The drones themselves are flown from separate bases in Afghanistan and Pakistan.

Because of its location near a hotbed of insurgent activity, the base is also a centre for recruiting and debriefing informants and it would not be unusual for local Afghans to be admitted to the facility for questioning, the report said.

Forward operating bases in Afghanistan depend on locals for security. But insurgents have frequently infiltrated the ranks of Afghan security forces as well as private firms hired to guard US facilities or to perform more menial tasks.

BBC reported that the suicide bomber had been courted by the US as a possible informant. US intelligence sources told BBC in Washington that the bomber had not undergone the usual full body search before entering the base and was able to smuggle in an explosive belt.

New York Daily News claimed that the bombing was likely vengeance from a local Taliban tribal warlord who was once the agency's ally.

The report noted that in the past year, CIA drones had killed Commander Jalaluddin Haqqani's relatives in safe-houses used by Al Qaeda leaders, which served as a motivation for Haqqani to attack the drone base.

The New York Times reported that in recent months CIA officers at the base had begun an aggressive campaign against the Haqqani group, which has claimed responsibility for the deaths of dozens of American troops.

The Washington Post noted that the Taliban received information about the US base from Afghan soldiers working there, raising questions about “whether it is possible to sustain the loyalty and unity” of Afghan and Pakistani soldiers in operations against the local militants.

A US intelligence official confirmed to CNN that the casualties included a mix of people — CIA staff and contractors. The CIA considers contractors to be officers. Two of them worked for Xe or, a private security firm formerly known as Blackwater.