His brother confirms reports that sole person convicted of 1988 plane bombing that killed 270 people has died at home in Libya

Abdelbaset al-Megrahi, the former Libyan intelligence officer convicted of the 1988 Lockerbie bombing that killed 270 people, has died, his brother has said.

Abdelbaset's brother, Abdelnasser al-Megrahi, confirmed reports that he had died aged 60 after a long battle with cancer. Abdelnasser, who was at the house in Tripoli where his dead brother lay on Sunday, told the Guardian: "I don't want to talk right now, I am very upset, I don't really feel like talking. He's dead, that's it, what more do you have to know?"

In an interview with the Guardian earlier this year, Abdelnasser said that his brother, who had moved to the secret address from his large home in Tripoli, was innocent. "He really is ill, he is too ill to even change the channel on the TV, he is lying down all day."

The Scottish government and East Renfrewshire council are investigating the claims of Megrahi's death. The Foreign Office is awaiting their confirmation. Megrahi was the only man convicted of the bombing, which killed 270 people, including 11 on the ground, when Pan Am Flight 103 blew up over Lockerbie four days before Christmas in 1988.

There was no immediate reaction from the Libyan government.

Abdulkarim Morajea, spokesman for the Democratic Libya Gathering, a party with the secularist National Forces Alliance, said he hoped elections due on 19 June would produce a government that will fully investigate Lockerbie. "He [Megrahi] is just another page in how Libya is governed, a chapter in our history. But it is not a chapter that is closed, 270 people died there (at Lockerbie). If we have a proper government, I hope it will be investigated."

Abdelbaset al-Megrahi was sentenced to life in prison in 2001, but was released on compassionate grounds by the Scottish government in August 2009 after being diagnosed with terminal cancer. At the time, doctors estimated he had around three months to live.

Megrahi's release prompted accusations that it had been linked to UK attempts to forge new trade deals with Libya, then still led by Muammar Gaddafi, and prompted outrage in the US, home to most of the victims on board the flight, after he returned to Tripoli to a hero's welcome.

Carole Johnson, 68, from Greensburg, Pennsylvania, mother of Beth Ann Johnson, a 21-year-old American student on the plane, said at the news of Megrahi's death: "This is three years too late. While I'm happy that he is dead, long ago I left it in the hands of God. I know exactly where he is, and I know it is quite hot. I'm sure he and Gaddafi are reunited again.

"When a parent loses a child there is never closure. You find a way of coping, but to say closure indicates you are closing the door on what has happened, but it is never over. It is the closure of a chapter in the book, a long overdue chapter."

Frank Duggan, president of Victims of Pan Am Flight 103, said: "He was an unrepentant murderer and now I hope he will finally see justice."

But Jim Swire, whose daughter Flora was killed in the bombing, said the reported death was a "very sad event".

Swire, a member of the Justice for Megrahi group, believes there is evidence yet to be released that will prove Megrahi's innocence.

"I met him last time face-to-face in Tripoli in December last year, when he was very sick and in a lot of pain.

"But he still wanted to talk to me about how information which he and his defence team have accumulated could be passed to me after his death.

"And I think that's a fairly amazing thing for a man who knows he's dying to do."

Swire added: "Right up to the end he was determined – for his family's sake, he knew it was too late for him – how the verdict against him should be overturned.

"And also he wanted that for the sake of those relatives who had come to the conclusion after studying the evidence that he wasn't guilty, and I think that's going to happen."

David Ben-Ayreah, a spokesman for the victims of Lockerbie families, said: "I was told seven days ago by very good sources in Tripoli that he was slipping in and out of quite deep comas, that the secondary tumours had affected his abdomen and lower chest, and that he had had three blood transfusions.

"His death is to be deeply regretted. As someone who attended the trial I have never taken the view that Megrahi was guilty. Megrahi is the 271st victim of Lockerbie."

In August 2009, Kenny MacAskill , the Scottish justice secretary, said Megrahi was going home to die after release from Greenock prison, amid suggestions he had about three months to live.

He acted on the basis of a medical report provided to him by Andrew Fraser, the director of health and care at the Scottish Prison Service.

His report described the three-month prognosis as "reasonable", but stated that no one "would be willing to say" if Megrahi would live longer.

Scottish ministers have always insisted that their decision was made in good faith, on compassionate grounds alone and followed the due process of Scottish law.

After his return to Libya, Megrahi rarely appeared in public. His family had on several occasions said that he was near death, in what was seen as an attempt to justify his release.

Prior to Megrahi's death, reports suggested his prostate cancer had spread to his neck. Others said he had been kept alive with cancer drugs unavailable in the UK.

Megrahi lost an appeal against conviction in 2002 but was given a new chance in 2007 when the Scottish Criminal Cases Review Commission (SCCRC) referred his case back to senior judges for a second time.

Following a £1.1m, three-year investigation into the case, the commission said there were grounds where it believed a miscarriage of justice may have occurred.

The appeal in full got under way in April 2009, almost two years on from the SCCRC's referral, but was dropped by Megrahi two days before he was released.

The decision to withdraw from the court process removed one possible obstacle to his returning to Libya by another mechanism, under a prisoner transfer agreement, although it was on compassionate grounds that he was ultimately released.

The Justice for Megrahi campaign group has called for an independent inquiry to look again at the conviction.

The SCCRC's report, which raised questions about identification evidence that led to Megrahi's conviction, has not been made public, but the Scottish government has pledged to bring about a change in the law to allow the paperwork to be published.