OSLO, Norway -- A Danish cartoonist who has faced death threats for caricaturing Islam's Prophet Muhammad says he is back home after Norwegian police passed on some "worrying" information.

Kurt Westergaard, who lives under round-the-clock protection, declined to elaborate on whether police had passed along a security threat while he was on a book tour in Oslo. Norwegian security police would not comment except to say that Westergaard had been in Oslo on Monday but had left the country.

The 76-year-old has been repeatedly threatened since the Danish newspaper Jyllands-Posten published 12 cartoons of Muhammad in September 2005, putting Denmark on a collision course with the Muslim world. Outraged Muslims launched fiery attacks against several Danish embassies.

Islamic law generally opposes any depiction of the prophet, even favorable, for fear it could lead to idolatry. Westergaard's caricature, which showed Muhammad wearing a turban shaped like a bomb with a lit fuse, was considered among the most offensive of the cartoons.

Danish police say they have foiled several plots against the cartoonist. Earlier this year, a Danish court convicted a Somali man of terrorism and sentenced him to nine years in prison for breaking into Westergaard's home armed with an ax in 2010. Westergaard locked himself inside a panic room and was unharmed.

Westergaard, who has bodyguards posted outside his home, had come to the Norwegian capital for a book launch Tuesday. Norwegian media reported he had suffered a heart attack and had to cut short his visit.

"That's the official version," Westergaard told The Associated Press by telephone from Denmark. "You can think what you like, but I'm fine, really. I'm OK."

Westergaard declined to comment on speculation there had been a security threat.

"You know, the security police take very good care of me," he said. "I took what the police told me seriously. I was worried."