''[This is] foul,'' Interior Minister Anders Ygeman told the Swedish news agency TT on Thursday. ''We are not doing enough to protect regardless of whether it is a mosque or other religious communities,'' he added.

''If it is true that the attack is caused by arson, then it is a direct attack against religious freedom in our country,'' Culture Minister Alice Bah Kuhnke was quoted as saying by Swedish local newspapers on Thursday.

Expo, a Swedish foundation raising awareness of racism and xenophobia, revealed that at least 12 attacks on mosques across Sweden took place this year.

This means that there was at least one attack per month on a mosque in each of several cities across Sweden from January to December this year, according to Expo’s figures.

People who visit these mosques do not always tell the authorities about the attacks,'' Daniel Poohl, editor-in-chief at Expo, told the Swedish daily newspaper Aftonbladet on Thursday.

Although the previous attacks this year on mosques across Sweden have not been as dangerous as Thursday’s arson, they do include: Vandalizing, breaking windows, lighting carpets inside the mosque on fire, and drawing swastika symbols on the entrance of the mosque, according to Expo.

''There is a big problem in Sweden with a part of the population not being able to practice its religion safely inside a house of worship,'' Poohl said.

Witnesses said Thursday’s fire broke out inside the Eskilstuna mosque when an unidentified individual hurled an object through one of the mosque's windows.

Between 15 and 20 people were inside the mosque in Eskilstuna on Thursday when the fire broke out at midday, and victims with injuries ranging from smoke inhalation to lacerations were taken to an area hospital, police told a news conference.

Abdirisak Hussein, a local resident who regularly prays in the mosque, told Swedish daily newspaper Dagens Nyheter that both adults and children were inside when the fire broke out.

''People are very shocked,'' Hussein told Dagens Nyheter. ''The only joy in this dark episode is that people got out so fast.''

'’This is a cowardly attack on religious freedom and on individuals,'' Sweden's Justice Minister Morgan Johannson told Swedish daily newspaper Aftonbladet. ''We cannot accept this in Sweden.''

 ''Our country must stand up against xenophobia and Islamophobia, and stand for basic human rights,'' Johansson added.

- Rise of the far right

The arson attack happened on Christmas Day amid tense a debate in Sweden on immigration and increasing support for the Sweden Democrats, a far-right political party.

The far-right and anti-immigration Sweden Democrats gained 13 percent of the votes in the September elections. This more than doubled its support since the last parliamentary elections in 2010 and made the party the kingmakers of the Parliament.

Experts say that one of the reasons behind the Sweden Democrats' increased popularity is its stance against immigration in Sweden, which is expecting 80,000 asylum seekers in 2014, according to the Swedish Migration Board.

The Sweden Democrats have vowed to cut immigration heavily, claiming this would save the Swedish government 151 billion Swedish kronor ($21.9 billion) within four years.

- 'Love bombardment'

While the police is still investigating the attack, and no suspect has been arrested yet, an anti-racism community in Eskilstuna encouraged people on Friday to place hearts on the burnt mosque.

The group called Together for Eskilstuna said on its Facebook website on Friday: ''To show our support for both the people who were inside the building at the time, and for all people who are Muslims, Together for Eskilstuna will go to the site to put up hearts, and we urge all to do the same.

''We stand up for a city where no one should have to feel fear because of their faith,'' the group said. ''We stand up for a city where we live together on equal terms.''

World Bulletin/News Desk