Italy closed its embassy in Libya on Sunday and stepped up its call for a U.N. mission to calm the worsening conflict there as thousands of migrants approached Italy by boat from North Africa.

Libya is unravelling, with two rival governments operating their own armed forces under separate parliaments, nearly four years after the civil war that ousted leader Muammar Gaddafi.

"The deteriorating situation in Libya made it necessary to close (the embassy)," Foreign Minister Paolo Gentiloni said. Embassy staff have been sent back to Italy, the ministry said. About 100 Italians were evacuated on a vessel escorted by the navy, the foreign ministry said.

Violence appears to be intensifying in Libya, where Islamic State is also active. The militant group released on Sunday a video that purported to show the beheadings of Egyptian Christians it had kidnapped in Libya.

The violence is particularly alarming to Italy because the two countries are separated only by a narrow stretch of the Mediterranean, across which migrants travel looking for a better life in Europe. Chaos in Libya has made it almost impossible to police traffickers who charge up to $2,000 for the passage.

Italy's coast guard, which was involved in a full-scale search and rescue mission until last year, has gone to rescue more than 2,000 people since Friday, days after more than 300 people died trying to make the crossing.

On Sunday, a speedboat carrying four people armed with Kalashnikov rifles approached a coast guard cutter carrying out a rescue, Italy's transport minister Maurizio Lupi said.

The armed people threatened the mariners to let them take back and re-use the migrants' boat, Lupi said, "another terrible development in the horrendous trafficking of men, women and children in the Mediterranean".

Defence Minister Roberta Pinotti said in an interview with Il Messaggero newspaper on Sunday that groups in Libya that have been infiltrated by extremists should be "anaesthetised".

Italy, which once counted Libya as a colony, had only made vague statements about willingness to lead a U.N. mission in Libya until Friday, when Gentiloni said it was "ready to fight" there.

Prime Minister Matteo Renzi, who has long called for more help from the EU to deal with migrants and for U.N. intervention in Libya, told RAI TV in an interview on Saturday: "The problems cannot all be left to us because we are the first, the closest, the people who pick up the boats."

Italy on Sunday also said it was willing to lead an international coalition against jihadists in Libya, as it began repatriating its citizens from the troubled north African country amid security concerns.

Rome on Friday warned its nationals against travelling to Libya and urged those already there to leave in the face of mounting insecurity as jihadists gain ground.

Defence Minister Roberta Pinotti said in an interview published Sunday that Italy was ready to lead a coalition from Europe and north African states to battle against the advance of jihadists in the violence-plagued country.

"We have been discussing this for months but now it has become urgent," Pinotti told Il Messaggero newspaper.

On January 23, Army Recognition announced that France could launch a military intervention in Libya within three month. Maybe the begining of a coalition...