BEIRUT (AP) -- A roadside bomb in Syria killed a local al-Qaida leader and his wife, activists said Tuesday, an attack that could ignite a new round of infighting among disparate rebel groups in the country.
The commander, identified as Ali al-Nuaimi of the Nusra Front, was killed near the town of Busra al-Sham in the southern province of Daraa, said Omar al-Hariri of the pro-rebel Sham News Network. The Britain-based Syrian Observatory for Human Rights also described the killing as an "assassination."
The Nusra Front did not mention the attack on the social networks it typically uses.
There was no immediate word on who was behind the attack, but activists said both rival rebels and the government are possible culprits. The killing comes amid rising tensions in the south between the Nusra Front, which is al-Qaida's affiliate in Syria, and more moderate rebels.
On Friday, Nusra fighters seized a Western-backed Syrian military commander, Ahmad al-Naimeh. Soon after, a group calling itself the "Islamic Courts of the Eastern Areas -- Daraa" said it was holding al-Naimeh and another military commander and would air their "confessions," without saying why they had been seized.
It wasn't immediately clear whether the bombing and the kidnapping were connected. But if they are, they risk igniting rebel infighting in the south between more moderate Syrian opposition fighters and the hard-line Nusra Front.
Meanwhile, activists said negotiations were continuing to evacuate rebels from opposition-held parts of the embattled central city of Homs, which Syrian government forces have been besieging for more than a year.
The activists, who are from the Homs region, said Tuesday that Iranian and Russian representatives have been attending the meetings at the al-Safir Hotel in the city. 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 seized by rebels in the northern province of Aleppo.
Russian and Iranian government officials were not immediately available for comment. Both Moscow and Tehran are staunch allies of Syrian President Bashar Assad.
Activists provided The Associated Press 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.
The activists said negotiators were still working out minor but key details of the evacuation, including how to guarantee the rebels' safety as they leave. The activists spoke on conditions of anonymity for their own security.
As the talks drag on, the rebels wait, exhausted, said one activist who goes by the name Abu Reem al-Homsi.
"We reached a situation where we would either die from shelling, hunger or in suicide missions. We were eating grass," al-Homsi said from the opposition-held Shayyah neighborhood. "We reached the end."
Now in its fourth year, Syria's conflict has killed more than 150,000 people and forced some 2.5 million people to flee to the country. More than 1 million have landed in neighboring Lebanon, which is struggling to accommodate them all.
The U.N. agency that helps Palestinian refugees, UNRWA, says that 50,000 Palestinians from Syria have registered with the agency in Lebanon.
On Tuesday, UNRWA spokesman Chris Gunness expressed concern about increased restrictions on Palestinian refugees after Lebanese authorities returned 41 Palestinians to Syria last weekend. Gunness said the agency is monitoring the border situation and that Lebanon has provided assurances that the restrictions are temporary.
Lebanese government officials did not immediately comment.
Palestinians living in Arab countries -- including a half-million Palestinians in Syria -- are descendants of the hundreds of thousands who fled or were driven from their homes in the war that followed Israel's creation in 1948.
In the Syrian capital Damascus, a barrage of mortar shells slammed into residential neighborhoods in the city center Tuesday, killing one man and wounding 23 others, the state news agency said.
Witnesses said several rounds landed about 50 meters (yards) from the Four Seasons Hotel, sending gray smoke into the air. People dove into building entrances to hide. Some frantically tried to back up their cars as police hurriedly closed off streets to avoid further casualties.
Rebels in the capital's suburbs appear to have stepped up mortar attacks in recent weeks.
Mortar rounds also struck the Jamiliyah and Saadallah al-Jabiri square in the government-controlled half of the northern city of Aleppo, killing seven people and wounding 30.
Associated Press writers Barbara Surk and Ryan Lucas in Beirut, and Albert Aji in Damascus, Syria, contributed to this report.
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