About 20 members of a Pakistani Islamic youth group protested on Friday over a sketch of the Prophet Mohammad published in a Swedish newspaper, witnesses said.

Pakistan condemned on Thursday what it described as an offensive and blasphemous sketch and summoned the Swedish charge d'affaires in Islamabad to lodge a protest with him.

Muslims believe images of the Prophet Mohammad are forbidden.

Cartoons of the Prophet published in Danish newspapers sparked widespread anger and deadly protests in several Muslim countries, including Pakistan, in early 2006.

The protesters in the city of Karachi gathered outside the press club, a traditional venue for demonstrations, and chanted slogans and burnt an effigy, witnesses said.

It was not clear who the effigy was meant to represent.

The sketch was published in the Swedish newspaper Nerikes Allehanda a week ago.

The Swedish Foreign Ministry said all Swedish embassies had been contacted this week and asked to remain vigilant.

"We have asked our embassies to follow constantly developments abroad," a Foreign Ministry spokeswoman said.

About 300 Muslims demonstrated peacefully on Friday outside the newspaper's office in Orebro, central Sweden. Muslim representatives spoke to the editor of the newspaper and agreed to start a dialogue.

Pakistan has said such drawings were a deliberate insult to the world's Muslims and they undermined efforts to promote respect and understanding between people of different religions.