"We are taking this seriously and cooperating closely with the Defence Forces, but is not exceptional. Similar threats have been made before," Supo's chief of communications, Liina Lehto-Seljavaara, told YLE.

She added that Supo is examining the matter and preparing to take measures, but did not specify what those measures are.

"We are looking at the individual and the pseudonym," she said, adding: "The threat to Finland is small."

Blogger Calls for Strikes

A number of provincial newspapers in Finland reported that Al-Qaida leader Abu Sulaiman al-Nasser blogged that Al-Qaida should strike against Finnish "crusader" troops in Afghanistan. He described the Finnish troops as "weak, trying to avoid conflict and the Finnish public shows little support for the Finnish ISAF troops".

The communications unit at the Finnish Defence Forces' General Headquarters said that no change had been noted in the security situation of Finnish troops in Afghanistan.

Finland has around 195 peacekeepers in Afghanistan.