Washington (CNN) -- Four U.S. senators have requested a formal meeting with British Prime Minister David Cameron during his visit to the United States this week to discuss the 2009 release of a Libyan man convicted of playing a role in the bombing of Pan Am Flight 103 over Lockerbie, Scotland.
It was unclear Monday if Cameron would meet with the four senators on Tuesday, when he will hold talks with President Barack Obama and also meet with Senate leaders.
According to a statement issued by Sen. Robert Menendez of New Jersey, one the four requesting the meeting, Cameron turned down the request.
However, the press secretary at the British Embassy, Martin Longden, told CNN in a statement that no final decision had been made.
"As you would expect on the eve of his visit, we now have a full program of meetings for the prime minister, so it will be very difficult to add additional meetings at this late stage," Longden's statement said. "But the (prime minister) is scheduled to meet with the Senate leadership on Tuesday afternoon and I am confident that he will want to talk this through with them."
The 1988 bombing of the Pan Am flight killed 270 people, most of them Americans. The flight was headed from Frankfurt, West Germany, to New York via London, England, when it exploded in the air.
Abdelbaset Ali Mohmed al Megrahi was convicted in the case and sentenced to life in prison. The Scottish government released al Megrahi on compassionate grounds last August after doctors said he had terminal prostate cancer and just three months to live.
Al Megrahi is still alive, and news reports in recent days have questioned whether he was as sick as depicted. Questions also have been raised about whether a deal was cut to release him to protect British business interests in Libya.
Cameron has said that al Megrahi's release was "completely and utterly wrong."
Longden's statement Monday said that Cameron "is very conscious about the depth of feeling around this issue. He's been very clear about his own view that Megrahi's release was a mistake, which he opposed at the time."
The four senators from New Jersey and New York -- Menendez, Frank Lautenberg, Kirsten Gillibrand and Charles Schumer -- released a letter Monday calling for the United Kingdom to launch a full investigation into al Megrahi's release and whether oil giant BP was involved.
In the letter, the senators express concern about correspondence between the British, Scottish and Libyan governments regarding al Megrahi's release to Libya and add, "We have also been dismayed to hear from a BP representative that the company actively lobbied the previous government on behalf of the PTA (Prisoner Transfer Agreement), and media reports suggest BP even tried to address the release of this individual."
Secretary of State Hillary Clinton added her voice to the senators' call for more investigation into the circumstances of al Megrahi's release.
"We are encouraging the Scottish and British authorities to review again the underlying facts and circumstances leading to the release of al Megrahi and to consider any new information that has come to light since his release," Clinton said in a letter to the senators.
Her letter reiterated the U.S. government's opposition to the Scottish decision to release al Megrahi on compassionate grounds, saying, "we do not believe the decision ... was in the interest of justice, and we continue to believe his freedom is not in the interest of justice."
Britain's ambassador to the United States, Nigel Sheinwald, said Friday, "Claims in the press that Megrahi was released because of an oil deal involving BP, and that the medical evidence used by the Scottish executive (Scottish Justice Secretary Kenny McAskill) supporting his release was paid for by the Libyan government, are not true."
BP said it did express concern to the British government in late 2007 about the slow progress of a prisoner transfer agreement that Britain and Libya were negotiating, saying it could have had a "negative impact" on British commercial interests.
But the company has denied involvement in any talks with either the British or Scottish governments specifically about al Megrahi's release.
At the American senators' urging, the U.S. Senate Foreign Relations Committee has set a hearing date of July 29 to investigate all the circumstances surrounding the release of al Megrahi, including whether BP played a role. Gillibrand and Menendez serve on the Foreign Relations Committee. Menendez will chair the hearing.
CNN's Jill Dougherty contributed to this report.