Dozens of soldiers trying to defend an airport in Libya's second city were killed and scores wounded in bombings and clashes with Islamists, the army said Friday as the U.N. threatened sanctions.

Libya has been sliding into chaos since longtime leader Moammar Gadhafi was toppled in an uprising three years ago, with interim authorities confronted by powerful militias that fought to oust him.

The U.N. Security Council on Thursday threatened sanctions against those who reject peace in Libya in a bid to shore up U.N.-brokered talks on ending the violence.

U.N. special envoy Bernardino Leon held a first round of talks with rival politicians on September 29 that the council described as "an important step" toward a peaceful resolution in Libya.

At least 10 migrants from sub-Saharan Africa drowned Thursday and dozens more were missing after their boat sank in the Mediterranean offshore Libya, the coast guard said.

Between 80 and 90 people were rescued after the boat went down in waters east of Tripoli, a coast guard officer said, adding that survivors said there had been up to 180 people on board.

Seven Libyan soldiers were killed and more than 60 wounded Thursday in car bombings and clashes with Islamists around the airport in the restive eastern city of Benghazi, military sources said.

Two car bombs targeted an army convoy, killing three soldiers, while four others died in fighting with Islamist militiamen who control most of the city, they said.

Militias that control Libya's two main cities denounced Tuesday hard-won talks brokered by the U.N. aimed at ending a split that has crippled the violence-plagued country.

Parliament, which was elected June 25 and is dominated by anti-Islamists, is recognized by the international community but contested by a coalition of militias that control Tripoli and by Islamists in the eastern city of Benghazi.

U.S. aircraft have flown roughly 4,100 sorties in the air war against Islamic State militants in Iraq and Syria since August, including surveillance flights, refueling runs and bombing raids, a military officer said Monday.

The number of flights reflects the widening U.S.-led air campaign that began with a more narrowly-defined objective when it was launched by Washington on August 8. 

More than 3,000 migrants have died trying to cross the Mediterranean so far this year, more than double the previous peak in 2011, the International Organization for Migration said Monday.

Europe is by far the most dangerous destination for "irregular" migrants, the organization found in a report, with 3,072, or 75 percent, of the 4,077 registered migrant deaths worldwide since January happening in the Mediterranean.

Opposing factions in Libya's parliament held what the United Nations hailed as "positive" talks Monday on ending a split which has left the violence-plagued country with rival governments.

U.N. mission chief Bernardino Leon, at the end of the two-hour meeting, said the factions had "agreed to start a political process and to address all issues in a peaceful way with a very strong call for a complete ceasefire."

Clashes between two of the largest tribes in southern Libya killed at least two people on Sunday, a tribal leader told AFP.

"Violent clashes are under way in Sabha between the Awlad Suleiman tribe and the Gaddadfa" tribe of dictator Moamer Kadhafi who was toppled and killed in 2011, Sheikh Mohammed Issa al-Mubasher said.

A Ukrainian doctor and his wife have been kidnapped in the eastern Libyan city of Benghazi, a stronghold of Islamist militias, the Libyan health ministry said Thursday.

The ministry issued a statement denouncing the abduction as an "irresponsible act" and calling on the kidnappers to release the pair who worked at the city's Al-Houari hospital.