Syria conflict: Rebel reinforcements arrive in Qusair
Dozens of fighters have arrived to reinforce rebel units battling to hold off a Syrian government and Hezbollah assault on the key town of Qusair.
A source in Qusair told the BBC the number was far fewer than the 1,000 suggested by the interim head of the main opposition alliance, George Sabra.
But the arrival does contradict state media reports the town is surrounded.
Meanwhile, the UN Security Council added the jihadist rebel group al-Nusra Front to its global sanctions list.
The move by the al-Qaeda Sanctions Committee means al-Nusra is now subject to an international asset freeze, travel ban and arms embargo.
Al-Nusra has emerged as one of the most effective rebel fighting forces in the Syrian conflict and last month announced allegiance to al-Qaeda.
Western nations on the Security Council pushed the designation because they are trying to strengthen moderate forces in the opposition, reports the BBC's Barbara Plett at UN headquarters in New York.
But diplomats said none of the council members ultimately objected to the move, which had to be agreed by consensus, our correspondent adds.
Syrian state television said troops and Hezbollah fighters had captured the Arjun district of Qusair on Thursday.
The source in Qusair did not give precise figures for the rebel reinforcements for security reasons.
But he said it was significant that they had managed to get in at all, and that the news would encourage others to come to the aid of the rebels.
He also said the humanitarian situation in Qusair was worsening, with urgent need to get some 800 wounded people out for treatment.
An attempt to evacuate the wounded on Friday had failed, he added, as the convoy had come under attack, with nine people killed.
The source said that 80% of Qusair was still under rebel control, although this cannot be independently verified.
He told the BBC: "There are about 30,000 people in Qusair. The ones that are inside are stuck here, and most of them live underground... Sometimes there are two or three families living in one room.
"There is no water at all, because the Assad regime controls the water supply, and there has been no electricity for four months."
Mr Sabra, acting leader of the National Coalition for Syrian Revolutionary and Opposition Forces, insisted that "around 1,000 fighters from across Syria" had penetrated the town.
The Syrian Observatory for Human Rights, a UK-based activist group, said "hundreds" of rebels had broken through army lines north-east of Qusair.
Rebel coalition expanded
Earlier, the National Coalition ended marathon talks in Istanbul with a pledge to broaden its membership.
It will include more representatives of the rebel Free Syrian Army and other activists inside Syria, but correspondents say it failed to achieve many stated goals.
The coalition announced that its leadership council would be expanded, following widespread criticism that it was out of touch with events on the ground in Syria.
It adds 14 members of a liberal bloc led by Michel Kilo, 14 members of activists' groups from inside Syria and 15 members linked to the FSA.
However, the coalition postponed until June the election of a new leader to replace Moaz al-Khatib, who said in March he would resign, and the formation of an interim rebel government headed by Ghassan Hitto.
Before the announcement, the US had called for a decision on a new leadership and an expanded membership to "move forward in planning the Geneva conference".
US Secretary of State John Kerry said on Friday he was convinced the Syrian opposition would take part in the Geneva talks.
The US and Russia are pushing for a meeting to find a political solution to the conflict in the Swiss city next month, and their officials will meet next week to prepare the ground.
Mr Sabra insisted: "The Syrian Coalition will not participate in international conferences and will not support any efforts in light of Hezbollah and Iran's militia's invasion of Syria."
However, given the fractured nature of the opposition it is unclear whether this is the final word.
The BBC's Jim Muir in Beirut says a lot more needs to be done for the opposition to be in any kind of shape to attend any conference in a coherent manner.
He says that, by contrast, the Syrian government appears unified and confident.
On Thursday, President Bashar al-Assad told Lebanon's al-Manar TV, which is owned by Hezbollah, that Syria would respond in kind to any future Israeli air strikes.
He said Syria would "in principle" attend the peace conference in Geneva if there were not unacceptable preconditions.
A Russian contract to supply Syria with new S-300 air defence missile systems was being implemented, he added, without confirming any deliveries.
German Foreign Minister Guido Westerwelle on Friday urged Moscow not to endanger the prospects of the Geneva Conference by carrying out the missile shipment.
The S-300 is a highly capable surface-to-air missile system that, as well as targeting aircraft, also has the capacity to engage ballistic missiles.
Two Russian newspapers on Friday quoted defence sources as saying that it was unclear if any of the missile system would be delivered this year.
Russia's MiG company said it was also discussing the supply of more MiG-29 M/M2 fighter planes to Syria. General director Sergei Korotkov said the number would be "more than 10".
Meanwhile, Syrian state TV showed the bodies and identity cards of two Westerners it said were killed by government troops while fighting for the rebels in the north-western province of Idlib.
The family of an American woman later reported her death, naming her as Nicole Mansfield, a 33-year-old Muslim convert from the town of Flint, Michigan.
The UK Foreign Office said on Friday that it was aware of reports about a British citizen and was seeking further information.