The Arab League on Monday pressed on with its mission in Syria.
Turkey, which has openly called for Syrian President Bashar Al Assad to step down, meanwhile, called on the opposition to keep up its resistance through "peaceful means."
The opposition Muslim Brotherhood slammed the League after the pan-Arab organisation decided on Sunday to extend its observer mission.
"It is clear that the observer mission in Syria seeks to cover up the crimes of the Syrian regime by giving it the time and opportunity to kill our people and break their will," Brotherhood spokesman Zuhair Salem said.
After a meeting with the opposition Syrian National Council on Sunday in Istanbul, a foreign ministry spokesman in Ankara urged the opposition to carry on with their resistance.
"The Syrian opposition demands democracy and we told them during a meeting yesterday (Sunday) that this should be done through peaceful means," he told AFP, referring to Foreign Minister Ahmet Davutoglu's talks with the SNC.
At a meeting in Cairo the same day, an Arab ministerial committee gave its widely criticised observer mission to Syria the green light to carry on and pledged to boost the number of monitors.
The committee "decided to give Arab League observers the necessary time to continue their mission according to the protocol," which sets a one-month term, renewable with the agreement of both sides.
The ministers agreed to increase the number of observers and said they may seek "technical assistance from the United Nations".
The committee urged Damascus "to fully and immediately implement its commitments" under the Arab plan, calling on all parties "to immediately stop all forms of violence."
The head of the mission, General Mohammed Ahmed Mustafa Al Dabi, is to give a report to the League on January 19 on Syria's compliance with the peace plan, the ministers said.
Qatari Prime Minister Sheikh Hamad bin Jassem Al-Thani, who chaired the Cairo meeting, called on Syria to "take a historic decision" to stop the bloodshed.
A report by the observers discussed at the meeting showed that "killing has been reduced. But even one killing (is too much)," said Sheikh Hamad.
Sheikh Hamad said the League hoped to raise the number of observers to 300 "within the next few days" from around 163 now deployed.
A team of Arab League monitors has been in Syria since December 26, trying to assess whether Assad's regime is complying with a peace accord aimed at ending its deadly crackdown.
A Syrian television channel close to the regime, Dunia, said Monday that a convoy of Arab monitors had come under fire from a "terrorist group" in the Baba Amro district of Homs, a flashpoint city in central Syria, wounding a driver.
Ath-Thawra, another official paper, said the Syrian authorities would "continue to cooperate with the observers ... so long as the delegation continues to fulfil its role with full neutrality and objectivity."
Critics say the mission has been completely outmanoeuvred by the government and have called for it to pull out.
The Arab League has admitted to "mistakes" but defended the mission, saying it has secured the release of prisoners and the withdrawal of tanks from cities.
Sunday's meeting came amid further violence in Syria, in which at least 13 civilians were killed by security forces and 11 soldiers died in clashes with deserters, human rights activists said.
The Assad regime has consistently asserted the unrest is the work of armed rebels, not largely peaceful demonstrators as maintained by Western governments and human rights watchdogs.