Swedish police have detained a woman who sprayed an anti-Islam activist with a fire extinguisher as he held a Koran-burning protest outside the Iranian embassy in Stockholm.

Video showed the woman going up to Salwan Momika and spraying white powder at him before she was intercepted by plainclothes police who led her away.

Momika, who appeared stunned but unhurt, then resumed his demonstration, which had been authorised by police.

Police spokeswoman Towe Hagg said the woman, who was not identified by police, was detained on suspicion of disturbing public order and violence against a police officer.

Sweden KoranSalwan Momika, top left, during a demonstration outside the Iranian embassy (Fredrik Sandberg/TT News Agency/AP)

Momika, a refugee from Iraq, has desecrated the Koran in a series of anti-Islam protests that have caused anger in many Muslim countries.

Swedish police have allowed his demonstrations, citing freedom of speech while filing preliminary hate speech charges against him.

Prosecutors are investigating whether his actions are permissible under Sweden’s hate speech law, which prohibits incitement of hatred against groups or individuals based on race, religion or sexual orientation.

Momika says his protests target the religion of Islam, not Muslim people.

The Koran-burnings have sparked angry protests in Muslim countries, attacks on Swedish diplomatic missions and threats from Islamic extremists.

Sweden on Thursday raised its terror alert to the second-highest level, saying the country had become a priority target for terrorist groups.