Isis has offered two hostages – a Norwegian and a Chinese – “for sale”, indicating the possibility of killing them if no one would pay the ransom.

An advertisement appearing in the latest edition of the jihadist magazine Dabiq, said this was a “limited time offer”.

Dabiq showed pictures of the two men and said their governments had "abandoned" them both, but that ransom payments could secure their release.

Norwegian Prime Minister Erna Solberg said yesterday she would not yield to the group's demand for a ransom payment.

"Our goal is to get our citizen home. Let me be very clear - this is a very demanding case," she told a news conference.

She did not name the man but said he was in his 40s and had been held by several groups since he was first captured.

"The government is taking this very seriously," she said. "We cannot and will not give in to pressure from terrorists and criminals. Norway does not pay ransoms. That is a principle we cannot give up in meetings with cynical terrorists."

Payments of ransom would raise the risks that other Norwegian citizens could also be kidnapped, she said.