A string of suicide attacks in Syria by the Islamic State group has killed at least 40 people, mostly pro-regime fighters, in one of the jihadists' deadliest operations in months, a war monitor said on Wednesday.
"Three bombers with explosive belts targeted Sweida city alone, while the other blasts hit villages to the north and east," said the Syrian Observatory for Human Rights.
Rami Abdel Rahman, the head of the Britain-based Observatory, said the group then followed up with further attacks, seizing three of the seven villages it had targeted.
He said 26 pro-government fighters had been killed and more than 30 people wounded in the attack on populated areas close to Sweida city.
Syria's official news agency SANA confirmed the attack had killed and wounded people in the provincial capital.
State television also reported casualties in villages to the north and east, adding that the army was "targeting positions of the Daesh (IS) terrorist group" Sweida province's eastern countryside".
Abdel Rahman said unidentified warplanes were also targeting IS fighters in the area.
Despite pro-government forces ousting the group from urban centres in eastern Syria last year, surprise raids in recent months have killed dozens of regime and allied fighters.
The regime of President Bashar al-Assad has in recent weeks ousted rebels from a majority of the country's south, part of which borders the Israeli-occupied Golan Heights.
The regime controls almost all of Sweida province but IS retains a presence in desert areas of its north and east.
It is now closing in on a patch of territory in nearby Daraa province held by jihadist group Jaish Khaled bin al-Walid, which has pledged allegiance to IS.The group, which has around 1,000 fighters in the region, has been the target of an intense campaign of bombing by Russian and Syrian jets in recent days.
Hayat Tahrir al-Sham, a group made up mostly of ex-members of the former Al-Qaeda affiliate in Syria, also has a few hundred men in the south.
A Syrian military source accused Israel on Tuesday of firing at one of its warplanes as it carried out operations against jihadists in southern Syria.
Israel's army earlier said it had shot down a Syrian fighter jet that had infiltrated Israeli airspace, risking another escalation in the sensitive border zone.
The Observatory later said air operations had dramatically decreased following the incident.
The Damascus regime has long accused Israel of backing IS and other opposition factions.
Clashes raged Tuesday between regime troops and IS jihadists on the northern edges of the border town of Saida, the Observatory said.