European governments have agreed to synchronise their laws to bar citizens from going abroad to fight for Islamic State and other extremists.

A document signed by foreign ministers from the 47-nation Council of Europe requires countries to outlaw specific actions, including intentionally taking part in terrorist groups, receiving terrorist training or travelling abroad for the purpose of engaging in terrorism.

Analysts say European laws vary, with some countries such as France charging people with crimes if they plan to leave to join a violent extremist group, and others, such as in Scandinavia, lacking a legal way to prevent their citizens from becoming foreign fighters.

The measure is a protocol to the Council of Europe's convention on the prevention of terrorism, which has been signed by 44 of the organisation's 47 member countries, including all 28 European Union nations except the Czech Republic.

Thorbjorn Jagland, secretary general of the Council of Europe, said the new accord would help national governments take more effective action against a new and growing problem by providing "common legal ground".

"When, for instance, a foreign fighter or a suspicious person comes to a border, then it will be easier for the police at the border to contact police authorities from countries from which this person is coming," Mr Jagland said.

Moreover, he said, the agreement will set a uniform standard that makes the intention of taking part in a terrorist act a crime in itself.