The emails sent on Sunday also said that Štefánika Airport and Trnava train station in the capital Bratislava would be targeted.

The senders of the emails added that the attacks were inspired by the events of September 11, 2001, in which terrorists carried out four suicide attacks in the U.S. in hijacked planes.

The news comes as police have been carrying out searches of churches after emails also claiming to be from Islamic State said powerful explosives had been placed in two churches in the Košice region.

Last week, hundreds of schools across Slovakia also repeatedly received threatening emails.

Prime Minister Robert Fico said: “Of course we are taking security measures, but I refuse to talk to you about idiots because they are idiots.

“But on the other hand, we have to make an effort to assure the public, a completely unnecessary effort, because we are 99.9% sure it's total nonsense.

“Simply, someone is having fun at the expense of the government and at the expense of this state.”

Police have not yet commented on the latest case of threats.

In November last year, around 70 secondary schools were forced to evacuate after also receiving threatening emails.