TBILISI (Reuters) - Georgian President Salome Zourabichvili said on Monday she had filed a lawsuit in the Constitutional Court against a law requiring groups that receive funding from abroad to register as foreign agents, which sparked mass protests.

Zourabichvili reposted comments on Facebook by her representative in parliament saying the law violated a clause in the Georgian constitution requiring the government to take all possible efforts to join the European Union and NATO.

The EU has frozen Georgia's integration with the bloc as a result of parliament overriding a veto by Zourabichvili to pass the law in June.

The law requires organisations receiving more than 20% of their funding from abroad to register as agents of foreign influence, with stringent disclosure requirements and punitive fines for violators.

Georgian and Western critics call it a draconian measure to stifle dissent, inspired by similar legislation in Russia. The ruling Georgian Dream party says the measure is necessary to protect Georgia's sovereignty.

Zourabichvili, who was elected in 2018 with the backing of Georgian Dream before breaking with it over what she says is its insufficient support for EU integration, has become one of the foreign agent law's most vehement critics.

In recent weeks, she has made efforts to bring together a coalition of opposition parties aimed at voting Georgian Dream out of office at parliamentary elections on Oct 26.

(Reporting by Felix Light; Editing by Andrew Osborn)