Police presence has been beefed up in and around Lennart Meri Tallinn Airport as Estonia's Internal Security Service (KaPo) continue to investigate a bomb threat called in during the early hours of Monday morning against flights from Estonia to Germany.

Sometime after 2 a.m. early on Monday morning, Tallinn Airport and the KaPo received calls from a man calling himself a member of the Islamic State group, or Daesh, who announced his intention to blow up a plane en route from Tallinn to Germany within a week. The calls were made in English, from an Estonian cell phone number located on Estonian territory.

Immediately after receiving the call, the police conducted an extra security check in Tallinn Airport and on its outbound flights. Security measures at the airport were stepped up as well.

The KaPo opened a criminal investigation into the threat against aviation safety, the proceeding of which will be directed by the Office of the Prosecutor General. "Currently there isn't any other information indicative of actual danger besides the phone call, but we take these threats seriously," said State Prosecutor Inna Ombler.

"Although Daesh has not given advance warning of its attacks, we're stepping up security measures and have begun an operation to capture the person who made the threat," said KaPo Deputy Director Aleksander Toots.

The increased security presence at the airport is not expected to require more time of airport passengers, and all flights are currently departing from Tallinn Airport on schedule.