As the additional fighters moved in, activists accused the Assad regime of attacking the wounded being moved out of the town.
Syrian rebels get boost as new fighters arrive in Qusayr
As the additional fighters moved in, the beleaguered political opposition alliance, the Syrian National Coalition (SNC), finally agreed to a significant expansion of its membership in Istanbul, after eight days of deadlocked meetings that had brought it to the brink of collapse.
George Sabra, the acting SNC president, yesterday repeated his plea for urgent intervention to get civilians and the wounded out of the combat zone in Qusayr.
"We call upon the International Committee of the Red Cross, the Red Crescent, and all international organisations to help evacuate the wounded from Qusayr and establish safe corridors to deliver medicine, blood and oxygen," he said.
Heavy fighting has raged for two weeks around Qasayr as regime troops, backed by Hizbollah militants from neighbouring Lebanon, try to retake the strategically and symbolically important town.
Opposition activists say efforts to evacuate the wounded have been prevented by regime forces opening fire on medical convoys.
"There was chaos as we were trying to take people out, people were running in every direction, they didn't know where to go" Hadi Abdullah, a spokesman for the town, told the BBC yesterday.
He said nine people were killed and about 80 injured, mainly civilians, during an evacuation effort yesterday morning. There were now 900 wounded in Qusayr, and medical supplies had almost run out, he said.
Close to the Lebanese border, Qasayr lies near key Hizbollah territory and on the route linking Damascus to Al Assad regime strongholds on Syria's west coast. It has, for more than a year, been in rebel hands, serving as an important conduit for weapons to opposition fighters in the central province of Homs.
Despite outnumbering and outgunning rebel forces - by about 10 to one, according to a rough estimate made by president Bashar Al Assad and aired during a television interview on Thursday - predictions of a quick victory for regime forces have not materialised.
The Syrian Observatory for Human Rights, a London-based organisation monitoring the conflict, said "hundreds" of rebel reinforcements had broken through regime lines near the village of Shamsinn, north-east of Qusayr, losing 11 men in the process.
Approximately 1,000 extra rebel fighters entered the battle yesterday, according to Mr Sabra.
The arrival of more rebel troops has done nothing to ease desperate conditions for thousands of trapped civilians however.
Syrian state media said regime forces had foiled an attempt by rebel fighters to infiltrate Qusayr from Lebanon, inflicting "heavy losses" in the process.
Regime and rebels view the battle of Qusayr as a litmus test in the conflict. A decisive victory for Mr Al Assad and his allies, Iran and Hizbollah - the Shiite militia has deployed fighters to the battle - would bolster their claim of gaining momentum in the fight to suppress a two-year rebellion.
But with each day the rebels are able to hold out, the prowess of elite regime forces and Hizbollah - each of which dispatched their own reinforcements this week - gets undermined.
The role of Shiite militants from Hizbollah has added to spiralling sectarian tensions and, on Thursday, was cited by the SNC as the reason for refusing to take part in the proposed Geneva 2 peace initiative.
International supporters of the Syrian opposition, including Turkey, the US, Qatar, Saudi Arabia and France, have all put pressure on the SNC to attend the proposed talks, tentatively scheduled to take place this month.
Those same international backers also appeared to have played a major role in getting the SNC to expand its membership from 63 seats to 114, in a decision taken in the early hours of yesterday morning.
Under the deal, 14 new seats were allocated to opposition activist groups based inside Syria, 15 seats were given to the Free Syrian Army and 16 seats given to a liberal, secular block headed by veteran dissident Michael Kilo. The remainder was given to independents and members of the Syrian National Council, a major opposition faction.
The decision to expand had been fiercely resisted by a majority of existing SNC members, prompting a deluge of criticism, both from Syrian activists and international supporters of the opposition, who contrasted the desperate fighting in Qusayr with the divisive, self-interested politicking of rival opposition factions in five-star hotels in Istanbul.
"At last the opposition did something right: adding the members who will represent the grassroots activists was a good move," said an opposition campaigner in Damascus.
Also yesterday, the Russian Interfax news agency reported that Moscow might supply 10 MiG-29 fighter jets to Mr Al Assad's forces, in what would be a new supply contract of military hardware.
Russia, the principal international supporter of the Syrian regime, has been the major arms supplier Mr Al Assad but has insisted it is only fulfilling existing deals, not signing new ones.
However, a day after the Syrian president publicly suggested a consignment of advanced Russian anti-aircraft missiles were already in his hands, newspapers in Moscow reported that delivery was unlikely to take place until next year at the earliest.
Western backers of the Syrian oppositions have hesitated to provide them weapons over fears these could fall into the hands of Islamist rebel groups such as Al Nusra Front, which was yesterday slapped with an international asset freeze and arms embargo by the Security Council over its links with Al Qaeda in Iraq.