Updated

British and Scottish officials who have declined to appear at a hearing this week on the release of convicted Lockerbie bomber Abdel Baset al-Megrahi should reconsider in order to dispel "a cloud of suspicion" over the issue, two U.S. senators said Monday.

U.S. Senator Kirsten Gillibrand of New York and Sen. Robert Menendez of New Jersey, standing in Times Square along with relatives of some of those killed in the bombing, said it was important to get the facts surrounding the circumstances of al-Meghrahi's 2009 release. The senators are probing whether an oil exploration deal between oil giant BP and Libya influenced the decision. The Senate Foreign Relations Committee has a hearing scheduled for Thursday.

"The abundance of incredible coincidences surrounding al-Megrahi's release deserves a real open, transparent hearing," Menendez said Monday.

"A cloud of suspicion will hang over the entire issue at least until all the looming questions are answered," he added.

The senators, along with Sen. Charles Schumer of New York and Sen. Frank Lautenberg of New Jersey, met with British Prime Minister David Cameron during his visit last week to discuss the issue.

Al-Megrahi was convicted in 2001 of the Dec. 21, 1988, bombing that killed 270 people. He was sentenced to life in prison, but Scottish Justice Secretary Kenny MacAskill decided last August to release him on compassionate grounds because the Libyan was diagnosed with terminal cancer. The decision outraged victims' families and drew criticism from U.S. officials.

As Britain and Libya were negotiating a prisoner transfer agreement in the fall of 2007, there were several discussions between BP and former Justice Secretary Jack Straw or his office, officials at Downing Street and the British embassy in Tripoli. In September, BP acknowledged it had expressed concern to the British government about the progress of the prisoner transfer deal but said it had not raised the case of al-Megrahi.

BP signed a $900 million exploration agreement with Libya in May 2007.

Straw, MacAskill and Scottish First Minister Alex Salmond have all said they will not attend the Senate hearing.

The committee is also looking to hear from embattled BP CEO Tony Hayward. Menendez said BP had not yet responded to the committee's request.