The 33-year-old Norwegian now being hunted by a slew of international intelligence agencies associated in his youth with Oslo’s far-left Blitz movement, newspaper Dagbladet reports.

Despite his one-time radical credentials, he later worked as a child minder at a daycare centre in Oslo, the city where he was born and raised, and did not have a history of violence, the paper said.

He eventually became a member of the Green Party, according to the newspaper.

A source close to the suspect said he came to be viewed as an easily-led conspiracy theorist after the September 11th terrorist attacks in 2001.

His ideological priorities shifted after he married the daughter of a diplomat from a North African country, the paper said.

In 2008, he converted to Islam. He then underwent a change of lifestyle, giving up alcohol and breaking off almost all contact with his earlier friends.

He recently became a father, Dagbladet said, adding that his wife had travelled to her home country with their child.

Peter Neumann, a Professor of Security Studies at King’s College in London, said it was “not surprising” that the terrorist-in-waiting had sympathized with groups on the far-left.

“Converts are often on the look-out for something to which they can dedicate themselves, and they like to experiment with radical environments. They seek out a strong ideology that gives them meaning and structure,” Neumann said.

“In Norway, converting to Islam is probably one of the most rebellious things you can do,” he added.

Neumann further noted that western converts, aside from women who converted when marrying Muslim men, were overrepresented among jihadists.

The Sunday Times said Al-Qaeda in the Arabian Peninsula (AQAP) had recruited the Norwegian Muslim convert and given him terrorist training in Yemen, and that the group were believed to have selected a US passenger jet as a target.

"The Norwegian recruit goes under the Islamic name of Muslim Abu Abdurrahman," the newspaper said.

He recently spent several months in Yemen to complete his training, the paper said.

Intelligence services in Norway last week said the 33-year-old remained in Yemen and cannot be extradited as it is not a crime under Norwegian law to attend a terrorist training camp.

Sources from three European intelligence agencies told The Associated Press, which broke the story, that the man was “operational” and ready to strike.