Swedes expressing solidarity with Muslims have staged manifestations after a series of recent attacks on mosques.

In the city of Uppsala, where anti-Muslim rhetoric was scrawled onto a mosque wall on Thursday, hundreds of people pasted red paper hearts and messages of support onto the building's entrance ahead of Friday prayers.

A day before the so-called love bombing, police said a Molotov cocktail was hurled at the mosque without causing a fire.

Earlier this week, a mosque in Eslov in the south suffered partial damage after a blaze that police suspect was arson.

And on Christmas Day, five people were injured when a petrol bomb was thrown through a window of a mosque in the town of Eskilstuna.

In Sweden no one should have to be afraid when they practice their religion. Prime Minister Stefan Lofven

Hundreds gathered for rallies on Friday in the country's three major cities - Stockholm, Gothenburg and Malmo - under the banner "Don't touch my mosque" to condemn the attacks.

The attacks come as debate intensifies in Sweden over immigration and the integration of asylum seekers in the traditionally tolerant Scandinavian country, with a far-right party gaining popularity.

Mats Lofving, acting police chief, told Radio Sweden that police were taking three measures in the wake of the attacks: increased monitoring of mosques, increased dialogue with Muslim communities and priority given to investigation of mosque attacks in cooperation with the country's intelligence agency.

Lofving stressed however that it was too early to say whether the three latest incidents were to be considered as serious attacks.

"It could be anything from youthful want of judgment, boyish pranks, to deliberate and planned," he said.

Attacks condemned

Sweden's Social Democrat Prime Minister Stefan Lofven led condemnation of the latest attack.

"In Sweden no one should have to be afraid when they practice their religion," he told the TT news agency, saying the government would increase funding for securing places of worship.

According to the anti-racism magazine Expo, there have been at least a dozen confirmed attacks on mosques in Sweden in the last year and a larger number are believed to have gone unreported.

Sweden, a country of nine million, is expected to receive more than 100,000 asylum applications this year, breaking all previous records.

Last month, the far-right, anti-immigration Sweden Democrats, which became the country's third-largest in September polls, came close to bringing down the centre-left government in a parliamentary budget vote.

However, in a last-minute agreement on December 27, narrowly avoiding calling a snap election, the government and centre-right opposition parties cut a deal, effectively denying the Sweden Democrats influence over major policy - including over immigration.