Speaking in Birmingham, Mr Brown reiterated that the decision was one for the Scottish Government alone.
He rejected suggestions that his government put pressure on Scotland to release al-Megrahi early in an attempt to improve Britain’s trade links with Libya.
“On our part, there was no conspiracy, no cover-up, no double-dealing, no deal on oil, no attempt to instruct Scottish ministers, no private assurances by me to (Libyan leader) Colonel (Muammar) Gaddafi,” Brown said at an employment summit.
“We were absolutely clear throughout with the Libyans and everyone else that this was a decision for the Scottish government.”
Mr Brown described the scenes accompanying the bomber’s return as “despicable”.
A video of Megrahi being feted on his arrival in Tripoli was shown in the Libyan capital, as part of the celebrations of leader Colonel Gaddafi’s 40 years in power.
Mr Brown’s comments came as MSPs debated the bomber’s release. Scotland Justice Secretary Kenny MacAskill defended his decision to turn down Megrahi’s bid to be transferred to Libya, and to grant his request for compassionate early release.
“Based on the values, beliefs and common humanity that defines us as Scots, I allowed him to return home to die,” said Mr MacAskill.
Mr Brown defended his refusal to voice publicly his opinion on Megrahi’s release, and said he had “minimised” the pain for Lockerbie families.
He insisted: “Would it have been right to have spoken publicly about the issue before the decision when it was a matter for the Scottish government? No, we would have been wrong to intervene when it was a quasi judicial decision for the Scottish Government.
“After the decision was made, and after the despicable scenes at Tripoli airport, was I right to use my energies to minimise further unnecessary suffering for the relatives of Lockerbie victims and to prevent Libyan independence day being made into a celebration of Megrahi’s return? Yes, and as we saw yesterday, he did not appear at those events.”