* Former UN chief says he remains optimistic
* Syrian forces pursue drive against rebels in northwest
* Clinton to meet Lavrov
By Dominic Evans
BEIRUT, March 12 (Reuters) - U.N.-Arab League envoy Kofi Annan has ended talks with President Bashar al-Assad and left Syria with little sign of progress on halting the country's growing political bloodshed.
"I am optimistic for several reasons," Annan said in Damascus on Sunday. "The situation is so bad and so dangerous that all of us cannot afford to fail."
There was no clear response from Assad to Annan's "concrete proposals" for a ceasefire, dialogue and humanitarian aid. Assad told Annan opposition "terrorists" were blocking any political solution.
U.S. Secretary of State Hillary Clinton will meet Russian Foreign Minister Sergei Lavrov in New York on Monday when the U.N. Security Council holds a special meeting on Arab revolts.
Russia, long an ally of Syria, and China have blocked attempts to pass a Security Council resolution condemning Damascus for its attempts to crush a year-old rebellion by force, in which thousands have died.
Moscow and Beijing want any international blame for the violence to be apportioned more evenly. China's Assistant Foreign Minister Zhang Ming said in Riyadh on Sunday both Syrian sides should stop fighting and aid should be sent to strife-torn areas - but he also warned other states not to use aid to "interfere".
Saudi Arabia and Qatar have taken a hawkish line against the Syrian government.
Saudi Foreign Minister Prince Saud al-Feisal on Sunday repeated calls for the Syrian opposition to be provided with weapons. This was the only way to end the conflict without foreign intervention, he said.
"The regime in Syria is committing a massacre of its own citizens," he added, after talks with German Foreign Minister Guido Westerwelle in Riyadh.
"We cannot accept the completely unreasonable continuation of the atrocities being perpetrated by the Assad regime against its own people," Westerwelle said.
The United Nations says Assad's forces have killed more than 7,500 people in their crackdown on protesters and insurgents. Authorities say rebels have killed 2,000 soldiers.
Annan's mission coincided with a Syrian military offensive against opposition strongholds in the northwest.
Activists said at least four people were killed in the town of Idlib on Sunday after troops and tanks moved in a day earlier. Three soldiers and a civilian were also killed in fighting in the village of Janoudiya in Idlib province on Sunday morning, according to the Syrian Observatory for Human Rights.
State news agency SANA said "terrorists" shot dead a former boxing champion, Ghiath Tayfour, in the city of Aleppo and also killed a leading Baath Party member in Homs province.
Saudi Arabia and Qatar, which are both ruled by autocrats and espouse a strict version of Sunni Islam, are improbable champions of democracy in Syria. Riyadh has an interest in seeing Assad fall because this could weaken its Shi'ite regional rival Iran, which has been allied with Syria since 1980.
The exiled opposition Syrian National Council ruled out talks while Assad is in power.
"Negotiations can never take place between the victim and torturer: Assad and his entourage must step down as a condition before starting any serious negotiations," it said. (Editing by Andrew Roche)