Turkey turned up the heat on embattled President Bashar al-Assad on Monday as activists said at least 12 people were killed in raids by Syrian security forces.
The latest violence came as two people were reported wounded when buses carrying Turkish pilgrims on their way home from Mecca came under gunfire near the flashpoint city of Homs in central Syria.
Turkey's Prime Minister Recep Tayyip Erdogan warned Assad his days were numbered and that he could not stay in power indefinitely through the use of military power.
And in a signal of support for groups seeking to oust Assad, British Foreign Secretary William Hague met representatives of Syria's opposition for the first time, although he said it was too early for London to formally recognise them.
Russia for its part accused the West of provocative behaviour in the Syrian crisis, saying Western countries were telling the opposition to forget dialogue with the embattled president.
The two people were wounded when "Syrian soldiers" attacked the Turks travelling by bus back from the Muslim hajj pilgrimage in Saudi Arabia after taking a wrong turn near Homs, said the private CNN-Turk television station.
"We confirm that an attack took place in Syria," a Turkish foreign ministry official told AFP, without elaborating.
In the latest confrontations, at least 12 Syrians were shot dead in raids by security forces in the provinces of Homs and Hama, also in central Syria, the Syrian Observatory for Human Rights said.
The state news agency SANA said four "terrorists" were killed, including a suspect high on a wanted list, while also reporting that two judges were kidnapped in Hama.
Stepping up the pressure on one-time ally Assad, Erdogan said: "You can remain in power with tanks and cannons only up to a certain point. The day will come when you'll also leave."
"Someone shows up and says 'I'll fight and die.' Against whom will you fight? Will you fight against your Muslim brothers you rule in your country?" asked Erdogan.
The Turkish premier was referring to an interview with Assad published in London's Sunday Times in which the Syrian leader vowed to fight and die for his country if faced with foreign intervention.
US ambassador to Syria Robert Ford, who was abruptly withdrawn in October due to security threats, has delayed his return to Damascus until later in the year, the State Department said Monday.
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"We do still intend for him to go back," State Department spokeswoman Victoria Nuland said in Washington.
Ford had assumed a high profile in Syria, visiting the focal points of protests to show US support for democratic change.
The latest bloodshed in Syria came a day after Foreign Minister Walid Muallem brushed off the threat of civil war and looming Arab League sanctions.
Despite the threatened sanctions, Syria let pass a deadline at midnight on Saturday to halt what the Arab League has called its "bloody repression" by pulling its troops from the street and engaging in talks with the opposition.
The Saudi government on Monday pressed Assad to conform "fully" with the Arab League proposals.
In a statement carried by state news agency SPA, Riyadh underlined "the importance of ensuring the protection of Syrian civilians and stopping the killings and acts of violence."
The 22-member Arab bloc said its foreign ministers would hold crisis talks on Syria in Cairo on Thursday, after rejecting changes proposed by Damascus to its proposal to send an observer mission to the country.
The Arab League plan came in for criticism on Monday from Russia, a long-time ally of the Syrian regime.
Russian Foreign Minister Sergei Lavrov complained that while the Arab League had called for a halt to violence, Western capitals had been telling the opposition to refrain from dialogue with Assad.
In London, Britain's top diplomat said after meeting members of Syria's opposition that he had appointed an "ambassador-designate to conduct relations with them."
But Hague added that Britain was not yet ready to formally recognise the opposition because they lacked complete unity, were not in control of any territory, and "the international community has not yet reached that point."
Hague said after the talks he had reiterated that Britain wanted Assad and his regime to stand down, saying it would be "the best thing for the future of Syria."
"But I've also emphasised the importance to them of achieving a united platform and a unified body among the opposition."
Leading opposition group the Syrian National Council in a statement on Monday said the SNC would organise, in cooperation with the Arab League, a national conference to prepare for the transitional period in Syria.