Other leaflets and stickers with instructions on how to build firebombs called on the public to throw Molotov cocktails at shops selling US products.

Warning letter

Food stores in Soedertaelje received a letter two weeks ago in which the group warned of coming attacks, saying the previous fires were set ablaze to test the effect of firebombs, which it said were set to explode after a certain amount of time.

No injures were reported in the latest fires, which occurred after opening hours.

More than 80 firefighters battled the blazes which completely destroyed two of the stores.

No arrests have been made and the police say Global Intifada is only one of several leads being investigated.

All the supermarkets targeted in Soedertaelje were Swedish, but like most food stores they sell a number of US-produced products.

The US embassy in Sweden has issued a warning about "possible threats to American interests".

War protest

According to Swedish security police, Global Intifada has claimed responsibility for around a dozen arson attacks around the country, mainly targeting the interests of countries involved in the war in Iraq as well as Sweden's defence industry.

The group has said it was behind attacks on the Polish consulate in 2004 and vehicles belonging to the Danish and Russian embassies a year later.

Soedertaelje, a town of around 83,000 people, has become known worldwide after taking in more than 7,000 refugees from Iraq.