Group says kills Islamic State-linked Syrian rebel leaders

Syria's al Qaeda offshoot said on Monday it had killed leaders of an insurgent group it says is linked with Islamic State in a suicide bombing of its headquarters in the south of the country.

Nusra Front and Islamic State are the two most powerful rebel groups fighting government forces in Syria and have been fighting each other since 2013 largely because of a power struggle between their leaders.

A Nusra Front Twitter posting on Sunday night said Abu Ali al Baridi, the leader of the Yarmouk Martyrs Brigades, had been killed alongside other top leaders in a "heroic" suicide bombing, but gave no further details.

A source in the area said a suicide bomber had blown himself up in a building in the Yarmouk Martyrs' stronghold of Jamla, a town near the Syrian Golan Heights and close to the border with Israel and Jordan in southwestern Deraa province

Nusra Front also called on Islamic State fighters, who number about 2,000 and who have acquired a large arsenal of weapons including tanks seized from Syrian army garrisons in the border area, to surrender themselves, a source in the area said.

Along with fighters from Ahrar al-Sham, Nusra Front have been fighting the Yarmouth Martyrs for months, trying to more of the border area that was formerly patrolled by U.N. troops.

Baridi, known as "The Uncle", was purportedly shown in a video this year pledging allegiance to Islamic State's leader Abu Bakr al Baghdadi. But the Yarmouk Martyrs Brigade have publicly denied any ideological or organisational links with Islamic State, and say Nusra Front is trying to discredit them.

Yarmouk Martyrs Brigade gained attention when they abducted 21 U.N. peacekeepers from the Philippines in a demilitarised zone between Syria and the portion of the Golan Heights that Israel captured in 1967. They released them in March 2013.

The only known insurgent groups affiliated to Islamic State with a presence in the area are further east in Deraa province, in a rugged desert area known as Laja, north of the mainly Druze-inhabited city of Sweida.

Apart from territory controlled by Syrian government forces, large parts of the south are held by the Southern Front, a coalition of mainly Western-backed non-jihadist insurgent groups.