Sweden raised its terrorist alert to 4 from 3 on a scale that runs from 1 to 5, reflecting a “high threat”, said Sweden's domestic security service, SAPO, on Thursday.
It follows a series of international condemnations of Quran burnings in the Scandinavian country.
"The reason for this decision is the deteriorated situation with regard to attack threats to Sweden and the assessment that the threat will remain for a long time," the head of the SAPO, Charlotte von Essen, said in Stockholm.
It is the first time since 2016 that the country has changed its threat level to four, according to AFP. This decision was caused by several reasons including increased ISIS threats to carry out terrorist attacks in Europe.
In July, two men burned a Quran in front of the parliament in Stockholm. In June, this also happened in front of Stockholm's largest mosque.
Last week, a Molotov cocktail was thrown at the Swedish Embassy in Beirut, though it did not explode.
At the weekend, al-Qaeda called for attacks against the country.
Several countries have issued updated travel advice to those wishing to visit Sweden.
On Sunday, Britain's Foreign Office warned travelers that "terrorists are very likely to try and carry out attacks in Sweden."
On July 26, the US warned its citizens to be extra cautious when traveling to Sweden due to possible terrorist attacks.
