The Megrahi decision has been branded "perfidious, repulsive and sickening" by a group representing friends and family of the Lockerbie atrocity who are now organising a campaign on the internet advocating a boycott of Scotland and the UK.

The website stated: "The government of the United Kingdom has washed its hands of the entire affair, allowing the Scottish Government total freedom in taking this perfidious action against the families of the victims of Pan Am Flight 103.

"The actions of the Scottish Government are inexcusable. A man who is responsible for the mass murder of 270 innocent civilians must be held accountable for such a cold blooded and ruthless act. Freeing a terrorist in order to further ties with the tyrannical Libyan regime of Muammar al Gaddafi and to further the commercial interests of British Petroleum in that region is repulsive and sickening."

The website states "don't travel to Scotland or do business there (or in the United Kingdom in general) and don't buy any British or Scottish products," adding: "Americans need to respond to this outrageous miscarriage of justice and betrayal of the victims' families, who were mostly fellow Americans, by refusing to spend their tourist dollars in Scotland and avoiding any kind of business there.

"Boycotting is the only way to send a clear and direct message to both the Scottish and British governments that Americans will not tolerate such a flagrant betrayal."

Urging Americans to avoid BP petrol stations in the US and to boycott tourism and banking, the website states: "Mr MacAskill, the so-called Justice' Secretary of Scotland, you should be ashamed of yourself. You know nothing of justice, nor will we ever forgive your heinous action, and it is our sincere hope that the people of Scotland will strongly voice their opposition to what you have done.

"You have shown to the international community that your government and the United Kingdom as a whole will stop at nothing to pursue the neverending and relentless acquisition of oil revenues."

A spokesman for Alex Salmond said last night: "The strong and enduring relationship between Scotland and the United States will continue, as will the friendship between the American and Scottish people.

"One unattributed website is not a significant factor, when compared to the thousands of US citizens who visit and will continue to visit Scotland, and no responsible American will pursue this approach."

The Washington Post only included a paragraph at the bottom corner of its front-page referring to coverage inside.

And in Europe leading German newspaper Frankfurter Allgemeine Zeitung commented: "To reprieve a seriously ill prisoner is an act of humanity," while Die Presse in Austria said: "Humanitarian decency releases the convicted assassin al-Megrahi."

In Tripoli, despite jubilant scenes at the airport, the English-language Tripoli Post reported: "Many are blaming the Scottish authorities for not taking care of Megrahi's health while in prison.

"They speculate that he was left, on purpose, to die of his cancer."

The newspaper said of the Justice Secretary's announcement that Megrahi was going home to die: "This statement reads as if the Scottish authorities have made sure that Megrahi dies within days from his release.

"In other words, Libyans are now convinced that the Megrahi case could be viewed as a premeditated murder on the part of the Scottish prison authorities."