A roadside bombing in Syria killed a local al-Qaeda leader and his wife, activists said on Tuesday, an attack that may ignite a new round of infighting between rebel groups in the war-torn country.

The Britain-based Syrian Observatory for Human Rights said Ali al-Nuaimi of the Nusra Front al-Qaeda’s affiliate in Syria and his wife were killed overnight while travelling in the southern Daraa province.

The bombing took place near the town of Busra al-Sham, according to the Observatory, which described the killing as an “assassination.”

The pro-rebel Sham News Network also reported the incident and its Daraa coordinator, Omar al-Hariri, said it wasn’t immediately clear who killed al-Nuaimi. The Nusra Front did not mention the attack on the social networks it typically uses.

The attack came after Nusra fighters seized a controversial Western-backed Syrian military commander, Ahmad al-Nuaimi last Friday. It is unclear if the two men are related the al-Nuaimi is a large tribe in the area. Also, it wasn’t immediately clear if the two incidents were connected.

The bombing and the abduction risk igniting rebel infighting in the south between more moderate Syrian opposition fighters and the hard-line Nusra Front.

The abducted commander, Ahmad al-Nuaimi, was widely disliked by many rebels who accused him of abandoning his men in battle in the past and fleeing to Jordan.

A radical organization calling itself the “Islamic Courts of the Eastern Areas Daraa” has confirmed it has Ahmad al-Nuaimi and another military commander, saying it would soon air their “confessions.”

Meanwhile, activists said that negotiations were underway to evacuate rebels from opposition-held parts of the embattled central city of Homs, which Syrian government forces have been besieging for over a year.

The activists said on Tuesday that Iranian and Russian representatives have been attending the meetings in Homs. They said they were there because they were negotiating a prisoner exchange as part of the Homs deal that would free at least three Iranians and a Russian who were seized by rebels in the northern province of Aleppo.

Russian and Iranian government officials were not immediately available for comment. The two countries are staunch allies of Syrian President Bashar Assad’s government.

Activists provided AP with a video showing an Iranian woman they claimed was being held captive by the rebels. The video was uploaded on March 8 this year, but it wasn’t clear when the Iranians and the Russian were seized.

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