A total of three people were behind the fake Facebook account used to make the threat, which happened last Thursday.

"According to current information we have, the alleged threat is not in Estonia," Kaido Saarniit, head of the Police and Border Guard Board's (PPA) Northern Prefecture said, according to daily Õhtuleht, who added that three men aged between 31 and 70 have so far been linked to the account, with PPA spokesperson Kristjan Lukk adding that there was reason to suspect that one particular person was behind the threat.

Contacts with authorities outside Estonia have been made in an effort to track down the perpetrators in order to establish their motives, although not prosecution proceedings have so far been launched.

A total of 12 people have been interviewed in connection with the investigation, the paper said; the fact that the threat was made from abroad was one reason why the PPA decided that Kallas' life was in no immediate danger.

The Facebook post which made the threat against Kallas said that 20-30 people "with a prison mentality" would be sent to rape her, and noted that "You (Kallas) are a priority on the list."

Prime Minister Jüri Ratas (Centre) condemned the attack over the weekend. "There is no place in Estonian society for such crude threats, which constitute a serious blow to our people's sense of security," he said.

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