Tripoli, Jun 4 (IANS): Authorities of Libya's third largest city of Misrata on Wednesday announced new measures restricting the entry of foreigners to the city amid escalating attacks by Islamic State (IS) group, media reported on Thursday.

"Foreigners must obtain work permits and have local sponsors," a source with Misrata's local council told Xinhua news agency.

"The procedures would be enforced due to threats posed by IS affiliates who intensified their attacks on vital sites and military locations of the city."

Misrata has been targeted with suicide bombings several times. On Sunday, a suicide attack on the city's western gate killed five people and injured six.

An IS affiliate claimed on Twitter responsibility for Sunday's attack and identified the bomber as a Tunisian national.

Libya, a major oil producer in North Africa, has been witnessing a frayed political process after leader Muammar Gaddafi was toppled during the 2011 political turmoil.

The country is now deadlocked in a dogfight between the pro-secular army and Islamist militants, which has caused a security vacuum for home-grown extremism to brew.