Raymond Davis, was arrested on January 27 after shooting dead two Pakistani motorcyclists. -Reuters File Photo

WASHINGTON: US lawmakers threatened Tuesday to cut aid to Pakistan unless it freed an American detained over a shadowy shooting, as Washington intensified pressure on its uneasy war partner.

The United States has already warned that high-level dialogue would be at risk unless Pakistan releases US government employee Raymond Davis, who said he was acting in self-defence when he shot dead two men in Lahore last month.

Three members of the House of Representatives drove home the point on a visit to Pakistan, telling Prime Minister Yousuf Raza Gilani starkly that the US Congress was working on its budget and looking for areas to cut.

“It is imperative that they release him and there is certainly the possibility that there would be repercussions if they don't,” Representative John Kline, a Republican from Minnesota, told reporters on his return.

“It's entirely possible that a member of Congress would come down and offer an amendment to cut funding for Pakistan based on their detaining Mr. Davis,” Kline said.

“My guess is there would be a lot of support for such an amendment, frankly, because of the outrage of detaining an American with diplomatic immunity,” he said.

Asked if aid would be at risk if Davis stayed in custody, Representative Buck McKeon, who heads the House Armed Services Committee, said: “It very well could be.”

Davis was arrested on January 27 after shooting the two Pakistanis, saying he feared they would rob him. A third Pakistani was run over and killed by a US consulate vehicle that had come to assist Davis, according to police.

The incident has set off protests in Pakistan, where anti-US sentiment has long run high.

Shumaila Faheem, the wife of one of the two men who was gunned down, committed suicide on Sunday by taking poison.

Many observers have questioned whether Davis was an ordinary diplomat.

Pakistani police said he travelled around with loaded weapons and a GPS navigation system.

“This case exposes a kind of dark side of this relationship between Pakistan and the US, which is what feeds a lot of the suspicions,” said Shuja Nawaz, director of the South Asia Center at the Atlantic Council think tank.

Nawaz was not surprised by US officials' insistence on freeing the American, saying: “There are so many layers to this story, on who he was and what he was doing, so clearly they don't want him out of their sight.”

Secretary of State Hillary Clinton declined to meet Foreign Minister Shah Mehmood Qureshi at a weekend conference in Munich, in a show of displeasure over the case, diplomats said.

US officials have told Pakistan that the Davis case “has to be resolved before we can move to a higher level of discussion,” one diplomat told AFP on condition of anonymity.

Officials stressed that the United States has not suspended contact with Pakistan, a key partner in the US war effort in Afghanistan.

“We continue to engage the Pakistani government at the highest levels to seek resolution of this case,” State Department spokesman Philip Crowley told AFP.

“We continue to stress that the US diplomat has diplomatic immunity and should be released,” he said.

Clinton still met in Munich with General Ashfaq Kayani, the head of Pakistan's army, and President Asif Ali Zardari held talks on Monday with the US ambassador, Cameron Munter.

Pakistan's ambassador to Washington, Husain Haqqani, wrote on micro-blogging service Twitter that relations between the countries “have proved resilient in the past” and that the “strategic partnership will endure, notwithstanding challenges”.

President Barack Obama's administration has declared combating anti-Americanism and reducing the allure of extremists in Pakistan to be a top priority.

Congress in 2009 approved a five-year, $7.5-billion aid package meant to build schools, infrastructure and democratic institutions as Pakistan ended a decade of military rule.

In October, the Obama administration proposed another $2 billion in assistance for Pakistan's military, often seen as the key power center in the country.

Nawaz, the analyst, said the administration would need “powerful gestures,” including compensation for the families of the shooting victims, to help rebuild public sentiment in Pakistan.

But Nawaz said Pakistan's leaders also had themselves to blame for letting the case drag on, saying it had become a “political kickball” between the central government in Islamabad and the Punjab provincial authorities.