DAMASCUS: A bomb exploded in southern Syria on Wednesday killing 21 people, with sources variously blaming rebels and regime troops, as Washington urged a key opposition group to join peace talks.
In other violence, at least 41 fighters were Wednesday reported killed in clashes between Kurds and jihadists in the northeast of the country.
The Syrian Observatory for Human Rights said a pickup truck was passing through an area of the southern province of Daraa when the bomb exploded.
"Twenty-one people were killed in the Nawa area... among them four children and six women, in a blast that detonated as their vehicle went past Tal al-Jumua."
The Observatory's Abdel Rahman said they were members of three families that were most likely fleeing strife-torn Nawa.
Activists on the ground accused troops of planting the explosives, the watchdog added.
But state news agency SANA said "21 terrorists (rebels) were killed when they were booby-trapping a car" in Nawa.
Daraa is the cradle of the uprising against President Bashar al-Assad that broke out in March 2011 and morphed into a civil war that the Observatory says has killed more than 115,000 people.
Assad's troops are not the only forces being targeted by the rebels, with the Observatory reporting Wednesday that Kurdish fighters from several villages in oil-rich Hasake province are engaged in pitched battles with two rebel groups, the Al-Qaeda-affiliated Islamic State of Iraq and the Levant and Al-Nusra Front.
"At least 41 fighters were killed, including 29 ISIL, Al-Nusra Front and Islamist fighters," the Britain-based group said.
Also killed were "12 fighters from the Committees for the Protection of the Kurdish People" (YPG).
Clashes have raged for months in majority Kurdish areas, as ISIL has sought to expel the YPG from areas it controls.
Fighting also raged Wednesday south of Damascus, with the state media and the Observatory reporting that Syrian troops had recaptured the strategic town of Bweida.
The clashes come as the United States seeks to persuade a key opposition group to agree to attend a proposed peace conference in Geneva.
The stalled initiative, dubbed Geneva 2, has been proposed by Washington and Moscow.
But the Syrian National Council, the biggest bloc within the umbrella Syrian National Coalition, said at the weekend it would not join the talks planned for next month and would quit the Coalition if it attends.
The SNC said it was snubbing the talks because of the ongoing suffering of the ground.
The United States, which backs the opposition, has urged the SNC to drop its refusal to join the talks.
"There have been many ups and downs in this process," State Department spokeswoman Jen Psaki said Tuesday, "but we continue to press for the opposition to have a representative body at the Geneva conference."
Geneva 2 was first mooted in May, but has been repeatedly postponed due to wrangling among the opposition and a dispute on which countries should participate.
The situation has been exacerbated by a chemical weapons attack on Damascus suburbs in August that left hundreds dead.
Washington led other world powers in accusing Assad's regime of using the prohibited weapons and threatened military strikes.
While denying regime troops were behind the attack, Damascus agreed to allow international experts to destroy its massive chemical arsenal as it raced to avert a strike by US forces.
Acting under a subsequent UN Security Council resolution, the Organisation for the Prohibition of Chemical Weapons has begun destroying the weapons in an operation expected to last until mid-2014.
The OPCW said Wednesday that its inspectors have conducted verifications at 11 of 20 sites identified by Damascus.
It added that critical equipment and some Category 3 munitions had been destroyed at six sites.
Under OPCW classifications, these are "unfilled munitions and devices and other equipment specifically designed to aid the deployment of chemical weapons."
An added challenge to the Geneva process has been mounting rebel criticism of the Coalition.
On Wednesday, rebels in southern Syria said it had "failed" and announced they no longer recognise the group.
The video statement signed by nearly 70 groups comes after several key rebel movements in the north announced their rejection of the Coalition in September.
The inability of the Istanbul-based Coalition to secure weapons and much-needed humanitarian assistance has raised the ire of opposition activists and rebels.