US politicians and families of US victims of the Lockerbie bombing were uniformly outraged and dismayed by the Scottish government's decision to release Abdelbaset al-Megrahi to Libya on compassionate grounds.

The White House and the US state department emphasised that they had vigorously opposed Megrahi's release in discussions with their British counterparts.

"The United States deeply regrets the decision," said the White House spokesman Robert Gibbs. "As we have expressed repeatedly to officials of the government of the United Kingdom and to Scottish authorities, we continue to believe that Megrahi should serve out his sentence in Scotland. On this day, we extend our deepest sympathies to the families who live every day with the loss of their loved ones. We recognise the effects of such a loss weigh upon a family forever."

The secretary of state, Hillary Clinton, said: "The United States is deeply disappointed … Today, we remember those whose lives were lost on 21 December 1988 and we extend our deepest sympathies to the families who live each day with the loss of their loved ones due to this heinous crime."

Senator Frank Lautenberg, Democrat of New Jersey, said "It's an outrage, and heaven forbid that we are caving in for commercial needs to releasing prisoners who have committed terrible crimes. That sends a message out to terrorists."

Congressman Dan Maffei, who represents Syracuse, New York, where 35 of the dead attended university, said he was "shocked and disappointed that the Scottish government would release a known terrorist for any reason.

"I can't imagine what the families of the victims are going through. As allies against terrorism, it is crucial that we form a hard line against these types of actions, and the release of al-Megrahi sets a very dangerous precedent."

More than 30 of the 189 Americans who perished on the flight were from the state of New Jersey.

Many families of the victims were horrified at the release and expressed their outrage in strong terms.

Susan Cohen, mother of Theo Cohen, a 20-year-old Syracuse University student killed in the bombing, described the release as "an absolutely disgusting disgrace". She speculated that the west's interest in Libyan oil played a role in the decision.

"Do you know how it's going to look in the history books for Scotland to have caved like this?" she asked. "This is what [Libyan leader Muammar] Gaddafi wanted. Megrahi will be a hero in Libya. Gaddafi will roll into New York in triumph in late September [for the UN general assembly].

"Megrahi in jail was a tiny, tiny bit of justice. It's now all gone and Gaddafi has won."

Bob Monetti of Cherry Hill, New Jersey, whose 20 year-old son Rick was on the plane, said: "Personally I always thought compassion came just after somebody said 'forgive me,' and those are words I've never heard. Maybe some people are much more forgiving than I am."

Kathleen Flynn, whose 21 year-old son John Patrick was on the plane, decried the "twisted Scottish law where one minister can make a decision like this".

"Had we had the trial in the US would it have been different?" she asked.

Stan Maslow of Haddonfield, New Jersey, whose 30 year-old daughter Diane died on the plane, said the release is "heartbreaking".

"We've lived through this for 21 years," he told Fox News. "We've never had justice."

Frank Duggan, president of victims of Pan Am 103, a group that represents the families of the US victims, said he had been assured the Libyan government would give no public show of celebration.

"We were all afraid that this guy would go back to a hero's welcome," he said in a statement. "But there's going to be no dancing in the end-zone, as the expression goes."