The UK on Sunday warned its citizens going to Sweden of possible terrorist attacks in the Scandinavian country following Quran burnings by anti-Islam activists that have sparked outrage across the Muslim world.
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The British Foreign Office said Swedish authorities had successfully thwarted several attacks and made arrests.
"You should be vigilant at this time," it said, adding that "terrorists are very likely to try and carry out attacks in Sweden", especially in tourist areas.
The U.S. government also issued a travel advisory warning of potential terrorist attacks in Sweden.
In response, Sweden's National Security Adviser Henrik Landerholm confirmed the increased threats to Sweden since the burning of the scriptures.
In a statement, Landerholm said that "representatives of terrorist groups have called for attacks against Sweden. States and other actors have helped amplify such messages." He said extremists who previously considered Sweden a "legitimate target" now consider it a "priority." The statement did not name any specific threats.
Landerholm said there also were "indications" that various groups are planning other attacks against Swedish interests abroad, and cited the storming of Sweden's Embassy in Baghdad last month and an attempted attack on the diplomatic mission in Beirut last week.
The Swedish government and relevant authorities are "monitoring developments, taking a variety of measures and working closely with international partners to protect Swedes and Swedish interests abroad and to counteract the hate messages being spread about Sweden," he said.
Earlier this month, Sweden tightened border controls and presence at certain crossing points.
Landerholm said the storming of Sweden's embassy in Iraq on July 19, an attempted attack on its embassy in Lebanon on Aug. 9, and also the Aug. 1 shooting of an employee at a Swedish consulate in Turkey contributed to the risk assessment.
A recent string of public Quran desecrations by a handful of anti-Islam activists in Sweden, and more recently in neighboring Denmark, has sparked mass protests across the Muslim world.
Quran burnings are allowed under the Swedish constitution's free speech protections, but Muslims view the desecration of their holy book as blasphemous.
Swedish officials have repeatedly condemned the acts and have also debunked claims that the Swedish government commissions the burning of scriptures.
Last month, the Scandinavian country's domestic security service SAPOs said the overall security situation has deteriorated and that the risk of terrorism in Sweden remains at an elevated level.