Saif al-Islam al-Gaddafi said the Lockerbie families had traded with "the blood of their sons and daughters" during negotiations over payouts for the deaths of loved ones.
Mr al-Gaddafi, who is seen by many as likely to succeed his father, also told BBC2's The Conspiracy Files the Libyan government had only taken responsibility for Britain's worst terrorist attack in order to get international sanctions lifted.
"You have to ask the families of the victims," he said. "The negotiation with them, it was very terrible and very materialistic and was very greedy. They were asking for more money and more money and more money."
He continued: "I think they were very greedy and I think they were trading with the blood of their sons and daughters."
But Dr Jim Swire, whose daughter Flora was one of the 270 people killed when Pan Am flight 103 from London to New York was blown up over Lockerbie on December 21 1988, said the compensation received by relatives could never make up for the loss of loved ones.
He said: "I just wish that the needs of the relatives, namely a thirst for the truth and for justice would be attended to, rather than an alleged hunger for money.
"So far as many relatives I know would say, we would gladly repay any 'compensation' money if we could just have our loved ones back.
"Financial 'compensation' must remain in its inverted commas. Money cannot buy our families back."
In a letter published in a newspaper today, Dr Swire said the Libyan government's admission of guilt for the Lockerbie bombing had allowed its economy to recover while giving the West access to the country's oil industry.
"The Libyans have achieved what they want and Western commerce has got what it wanted too," he said.
"In this, many of us feel like pawns."