Fear of "commercial warfare" from Libya led the British government to pressure Scotland to free the convicted Lockerbie bomber last year, reads a report being released Tuesday by four U.S. senators. 

The lengthy report, which calls on the British and Scottish governments to apologize for Abdelbaset al-Megrahi's release, concludes that a $900 million oil deal with Libya ultimately paved the way for the Scottish justice system to free al-Megrahi in August 2009. 

The report says that faulty medical analysis was used to justify his release on "compassionate" grounds, a decision described as a crass component of a complicated trade relationship between the United Kingdom and Libya. 

"The U.K. government played a direct, critical role in al-Megrahi's release," the report states. "The U.K. knew that in order to maintain trade relations with Libya, it had to give into political demands." 

The investigation was led by New Jersey Democratic Sens. Robert Menendez and Frank Lautenberg and New York Democratic Sens. Charles Schumer and Kirsten Gillibrand. The report comes on the 22nd anniversary of the bombing of Pan Am Flight 103 over Lockerbie, Scotland, an attack that killed 270 people, many of them American. 

Though convicted bomber al-Megrahi had been expected to die in prison, the Scottish government released him last year following a prognosis that he had just three months to live. Sixteen months later, the former prisoner with a terminal prognosis is still alive, reportedly living in a villa in Tripoli. 

Accounts about his current health are conflicting, but one recent report from Sky News quoted a source close to the family saying his death is imminent. 

Explanations about the release, challenged from the start by outraged U.S. officials, began to unravel within days after al-Megrahi was allowed to return to his country, where he was given a hero's welcome complete with a greeting on the tarmac by Libyan President Muammar al-Qaddafi. 

Regardless, the senators' latest report claims there was "no medical justification" for his release.

According to the five month investigation, the Scottish government ignored expert opinions challenging the three-month time frame, instead relying on doctors "without the necessary medical training or experience with prostate cancer to provide an accurate prognosis." 

The report suggests that a flawed prognosis may have been the goal all along as British officials allegedly scrambled to protect their country's commercial interests and future oil supply out of Libya. A 2007 oil exploration deal between BP and the Libyan government was of primary concern, according to the investigation, and in the end, the Scots felt pressure from the governments of Libya, the United Kingdom and Qatar to release al-Megrahi. 

British and Scottish officials have denied this. Britain's foreign secretary claimed over the summer that oil deals with BP were not a factor in al-Megrahi's release. BP has acknowledged expressing concern about a prisoner transfer deal with Libya, but claims it did not mention the specific case of al-Megrahi. 

The senators' investigation consisted of a series of interviews and inquiries. A staff delegation traveled to Britain to interview U.K. and Scottish officials, while investigators conducted separate interviews with experts and officials from the U.S. government. Menendez also led a Senate Foreign Relations Committee hearing in late September to explore the case. He invited Scottish and British officials to testify, but they declined.