|Arab ministers will meet on Sunday to review the proposed sanctions if Syria does not sign the protocol [Reuters]
The Arab League has given Syria until 11:00 GMT on Friday to sign a protocol allowing rights monitors into the country before it press ahead with plans to impose economic sanctions, according to Egypt's envoy to the regional bloc.
Turkey's foreign minister also added his voice to those calling for Syria to accept monitors on Friday, calling the Arab League utimatum a "last chance" for its neighbour.
"We think it is now vital to put an end to the suffering of the Syrian people," said Ahmet Davutoglu at a press conference in Istanbul.
Davutoglu hinted that he could attend a meeting of Arab League foreign ministers on Sunday at which possible sanctions could be discussed, and said Turkey was considering taking further steps against Damascus in conjuction with the bloc.
The sanctions could include a suspension of commercial flights to Syria and a halt to dealings with its central bank, Afifi Abdel Wahab said in Cairo on Thursday.
"Tomorrow [Friday} is the deadline for Syria to sign. If they don't sign, the economic and social council [of ministers] will meet on Saturday to discuss economic sanctions," he said.
Wahab's comments came after members of the Arab League convened in Cairo to discuss the escalating crisis in Syria in the wake of President Bashar al-Assad's refusal to end his crackdown on anti-government protesters.
Last week, Walid al-Muallem, the Syrian foreign minister, said the planned mission placed "impossible conditions" and gave the 500-member monitors' team too much authority that infringed on Syria's sovereignty.
In the run-up to Thursday's meeting, Lebanon said it would not endorse any potential sanctions against Syria.
"Lebanon will not endorse any sanctions by the Arab League against Syria," Adnan Mansur, the Lebanese foreign minister, told a local radio.
"We will decide whether to vote against or abstain depending on the talks in Cairo."
More deaths reported
Protesters have been rallying against Assad's one-party rule since March, braving the much-criticised security crackdown.
Activists reported that at least 28 people were killed by security forces across Syria on Thursday.
Of the dead, 26 people were killed in the central city of Homs, one in the central city of Hama, and one in the southern province of Daraa, according to the Local Co-ordination Committees activist network.
In-depth coverage of escalating violence across Syria
The UK-based Syrian Observatory for Human Rights said heavy machine gun fire blasted the city of Rastan following a one-hour clash early on Thursday between soldiers and army defectors.
The UN says more than 3,500 people, most of them civilians, have been killed since the start of the uprising.
Members of the Syrian opposition have been meeting world leaders, urging further action against Assad's government.
Alain Juppe, the French foreign minister, met leaders of the opposition Syrian National Council on Wednesday, describing the exiled group as "the legitimate partner with which we want to work".
Juppe said France would also seek EU backing for humanitarian corridors in Syria "to alleviate the suffering of the population".
However, he ruled out the possibility of military intervention to create a "buffer zone" in the north of the country.
International pressure has been mounting on Syria, with the UN General Assembly's Human Rights Committee condemning the crackdown in a vote on Tuesday.
The resolution, drafted by Britain, France and Germany, received 122 votes in favour, 13 against and 41 abstentions.
Arab states that voted for it included co-sponsors Bahrain, Jordan, Kuwait, Morocco, Qatar and Saudi Arabia, as well as Egypt.
Russia and China, which vetoed a European-drafted resolution that would have condemned Syria in the UN Security Council last month, abstained.
Moscow on Friday reiterated its opposition to additional sanctions and international pressure on Syria.
"At this stage, what we need is not resolutions, sanctions or pressure, but inter-Syrian dialogue," said Alexander Lukashevich, a foreign ministry spokesman.
Bashar Jaafari, the Syrian ambassador to the UN, said the resolution had no meaning for his country and portrayed it as a US-inspired political move.
"Despite the fact that the draft resolution was basically presented by three European states, however it is no secret that the United States of America is ... the main mind behind the political campaign against my country," he said.
"This draft resolution has no relevance to human rights, other than it is part of an adversarial American policy against my country."