The BBC's Daniel Sandford in Washington said "broadly" families in the UK were concerned about the conviction, whereas US relatives were convinced of his guilt.
American Susan Cohen, whose 20-year-old daughter Theodora also died, said: "Any letting out of Megrahi would be a disgrace. It makes me sick, and if there is a compassionate release then I think that is vile."
But Pamela Dix, from UK Families Flight 103, said there had been a "lack of justice" for the victims, which included her brother Peter.
She told BBC Two's Newsnight she was "baffled" by much of the evidence in the trial that led to Megrahi's conviction in 2001.
'Just a tool'
And Martin Cadman, who lost his son in the bombing, said he believed Mergrahi was an innocent man who had acted with others.
He said: "As far as I know the Scottish authorities and no-one else has done anything to try and find who these others were that were supposed to be implicated, so the whole thing is really very unsatisfactory".
Bob Monetti, a past president of the organisation Victims of Flight 103, lost his 20-year-old son Richard in the bombing.
He told BBC Radio's Good Morning Scotland programme: "We understand that Megrahi was just a tool in this. He wasn't really the person that decided what to do.
Glenn Campbell, BBC Scotland political correspondent
I understand preparations for Mr Megrahi's release are being made in time for him to be home with his family in Libya by Ramadan, which starts next Friday.
The Parole Board for Scotland has been asked to give its opinion on compassionate release.
The Libyan authorities - who have held high level talks with the Scottish justice secretary in recent days - have also been advised to make plans to fly Mr Megrahi back to Tripoli.
The Scottish Government is right to say "no decision has been taken" - but that should change in the next few days and the likelihood is Mr Megrahi will return to Libya by next weekend.
"But Megrahi was the one who was convicted and lost his appeal. So I am really happy to see him in jail and not happy to see him anywhere else."
It is believed UK and Libyan officials have held talks this week over Megrahi's appeal against his conviction.
The speed of his transfer is thought to be influenced by consensus among all parties that Megrahi be back on Libyan soil in time for Ramadan next week.
News of his release came after Scottish Justice Secretary Kenny MacAskill visited Megrahi in prison, amid speculation he might be moved to Libya.
A prisoner transfer request was made by Libya to the UK government last May, less than a week after a treaty allowing prisoners to be transferred between the two countries was ratified.
But a spokesman for Scottish First Minister Alex Salmond said: "No decision has been taken, either on the application for compassionate release or the application under the prisoner transfer agreement and so it is entirely speculation."
A Scottish Government spokesman added that a decision was expected from Mr MacAskill this month.
Mr MacAskill said last week he would miss the 90-day deadline, which expired on 3 August, because he was waiting for more information.
A prisoner transfer cannot take place if criminal proceedings are active, meaning Megrahi would have to drop his latest appeal against his conviction in order to be sent home.
It is difficult to see why the Scottish Government seems to have weighted the balance of compassion in favour of the criminal and against the interests of the victims, their families and the general public
Robert Brown Lib Dem justice spokesman
Scottish Liberal Democrat justice spokesman Robert Brown said: "If this decision is confirmed then it is wrong in principle, wrong in practice and sets the wrong precedent.
"This is a man who was convicted in a Scottish court under the eyes of the world of the worst atrocity in Scotland in modern times.
"In a case like this it is difficult to see why the Scottish Government seems to have weighted the balance of compassion in favour of the criminal and against the interests of the victims, their families and the general public."
Scottish Conservative justice spokesman John Lamont said it would be a "catastrophic decision" if Megrahi were to be released without compelling medical evidence that he was gravely ill.
South of Scotland SNP MSP Christine Grahame, who has visited Megrahi in prison, said he was "very ill" and was not expected to live beyond the end of the year.
She stressed she had no inside information whether he was to be released.
She said: "If it is the case, and it's still speculation, compassionate release is just not only for Mr Megrahi but the victims' families."
Ms Grahame said she had not spoken to him in recent days but he was getting "very ill and pretty desperate".
She also predicted that Megrahi's appeal would continue even if he was granted compassionate release.
Megrahi was ordered to remain in prison for a minimum of 27 years, having been found guilty of the bombing - the UK's worst terrorist atrocity.
Megrahi's legal team had also made a request for him to released from prison on compassionate grounds.
An earlier request, made in October 2008, was rejected by Appeal Court judges after they heard medical evidence that with adequate palliative care, Megrahi could live for several years.
The court heard that such requests are normally only granted where a prisoner has fewer than three months to live.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.