WASHINGTON - Drawn into an old disaster, British Prime Minister David Cameron said Tuesday he would not order a fresh investigation into why a convicted bomber was set free or whether BP had a role in it. President Barack Obama stood by his new peer but said that "all the facts" must come out.

In declaring his position - to potentially make public more information from an earlier investigation of the man's release, but not start a new one - Cameron politely but roundly rebuffed the U.S. government in his first White House visit.

Obama sought a diplomatic tone in response, saying the U.S. would "welcome any additional information," and made clear he wanted it. Beyond the lingering anger, the case swirls anew with interest because of its possible links to BP, the company facing huge fallout in the United States for causing the Gulf oil spill.

"I think all of us here in the United States were surprised, disappointed and angry about the release of the Lockerbie bomber," Obama said in a short news conference dominated by the topic. Yet he added: "The key thing to understand here is that we've got a British prime minister who shares our anger over the decision. And so I'm fully supportive of Prime Minister Cameron's efforts to gain a better understanding of it."

At issue is Libyan Abdel Baset al-Megrahi, who was convicted for the 1988 bombing of a jet over Lockerbie, Scotland that killed 270 people, most of them American. The Scottish government released the cancer-stricken man on compassionate grounds last year, igniting outrage on both sides of the Atlantic.

Bringing the matter to the fore again are accusations that BP sought the release of the convicted bomber as part of efforts to seek access to Libyan oil fields; BP has acknowledged that it urged the British government to sign a prisoner transfer agreement with Libya but says it never specified al-Megrahi's case.

"Any lobbying they might have done is an issue for BP, and an issue that they should explain themselves," Cameron said flatly.

The British leader said, though, that he has not see anything to suggest that the Scottish government was swayed by BP.

On Tuesday night, the four U.S. Democratic senators from New York and New Jersey met with Cameron for 45 minutes and left with the impression that a further investigation may not be out of the question.

British Embassy spokesman Martin Longden confirmed that Cameron had called for a review of documents about the case. Longden said indications are that due process was followed "but if evidence comes to light that casts any doubt on that, than the prime minister's clear - it should be properly investigated."

"We made the case that there's just too much suspicion here to sort of brush this aside," said Sen. Chuck Schumer, D-N.Y.

The issue overshadowed a broader agenda that Obama and Cameron discussed in the Oval Office and over lunch before addressing reporters. The 43-year-old Cameron, a few years younger than Obama, took power in May and leads a coalition government of his Conservative Party and the smaller Liberal Democrats.

He and Obama displayed a united front on the threat of a nuclear-armed Iran, the need for direct Middle East peace talks and the fight in Afghanistan.

But just ahead of Cameron's arrival in Washington, Secretary of State Hillary Rodham Clinton requested that the Scottish and British governments review exactly what happened in al-Megrahi's release. That seemed to go nowhere with Cameron, who said: "I don't think there's any great mystery here."

"There was a decision taken by the Scottish Executive - in my view, a wholly wrong and misguided decision, a bad decision, but their decision, nonetheless," he said. "That's what happened, and I don't think we need an extra inquiry to tell us that that's what happened."

Even Obama said whatever information emerges will likely lead to the same conclusion: "It was a decision that should not have been made," he said.

Al-Megrahi served eight years of a life sentence. He was released and returned to Libya in August 2009 after doctors said he had only three months to live, but a doctor now says he could live for another decade.

Cameron did say that his government would cooperate with the inquiry being pursued by the U.S. Senate Foreign Relations Committee. And the matter shows little sign of quickly fading away as long as BP is in the mix. The British prime minister said that he and Obama discussed the company at length.

In front of reporters, Cameron was notably more defensive of the British company than Obama. Cameron said BP must be responsible for responding to the Gulf disaster it caused and compensating victims, but he also described BP's success as vital to the British and U.S. economies and to thousands of workers.

"Let us not confuse the oil spill with the Libyan bomber," Cameron said, a point he emphasized more than once.

Late Tuesday, the White House said that Cameron had extended an invitation on behalf of Queen Elizabeth for Obama and first lady Michelle Obama to attend a state dinner in their honor in London.

White House spokesman Mike Hammer said the Obamas accepted the offer and that no date had been set yet.

Associated Press reporter Frederic J. Frommer contributed to this story.