Syria has agreed to extend a widely criticized Arab League observer mission for a second month, hours after launching an angry tirade against the bloc's efforts to mediate in the crisis.

League officials had warned that the monitors, already depleted by the withdrawal of the six Gulf states from the mission, would be confined to base from Wednesday if Syria's agreement was not forthcoming.

"Foreign Minister Walid Muallem sent a letter tonight to the secretary general of the Arab League (Nabil al-Arabi)informing him of the Syrian government's agreement to extend the observer mission for one month, from January 24 until February 23, 2012," said a statement on Tuesday carried by the official SANA news agency.

Announcement of the letter came after Muallem delivered a stinging attack on the League after its weekend call for President Bashar al-Assad to hand power to his deputy and clear the way for a unity government within two months.

The new plan envisioned the "peaceful departure of the Syrian regime" and resembled the arrangement in Yemen, where Gulf states convinced Ali Abdullah Saleh, the outgoing president, to delegate power and leave the country.

Muallem told a news conference on Tuesday that the latest Arab proposal was a violation of his country's sovereignty, and attacked the league's efforts to take its plan to the UN. He said the league was "implementing the conspiracy they have agreed to abroad against Syria."

UN meeting request

Western governments have been capitalizing on the Arab League's tough new stance to embark on a fresh drive for action by the UN Security Council after previous efforts were blocked by China and Russia.

European and Arab nations want a vote next week on a resolution condemning Syria's crackdown on protests and hinting at sanctions, diplomats said.

Britain, France, Germany and Arab nations are working on the resolution which could face Russian opposition because of a call on all UN member states to follow Arab League sanctions against Assad's government.

Diplomats from several Security Council and Arab nations said there could a vote as early as Monday or Tuesday next week.

The Arab League also formally requested a meeting with UN chief Ban Ki-moon in New York to discuss its plan for resolving the Syria crisis and to ask for the Security Council's support, according to Arab League deputy leader Ahmed Ben Helli.

Al Jazeera's Scott Heidler, reporting from the UN headquarters in New York, said that Western nations would be pushing a new draft resolution to be presented to the Security Council later in the week.

"Russia and China vetoed previous resolutions on Syria... but in light of the Arab League resolution on Sunday, it will be interesting to see if that changes," he said.

"If we look at the Security Council resolutions in Libya, what really was the turning point is the regional call for UN assistance. There is a regional call now for the UN support [in Syria]."

At his news conference, Muallem signalled that the crackdown on dissent will continue, saying Syria's government has a "duty" to confront armed groups.

"It is the duty of the Syrian government to take the necessary measures to address the problem of those armed elements who are wreaking havoc throughout Syria," he said.

Referendum on constitution

He also said that while sanctions imposed on the country are causing an economic crisis there, Damscus would not yield to such pressure.

"There is no doubt that any kind of sanctions affect the population, but they do not affect the political situation," he said.

The government is blaming the unrest, which the UN estimates have killed more than 5,000 people since March last year, on "terrorists". Authorities say more than 2,000 members of the army and security forces have been killed.

Muallem said Syria will hold a referendum on a new constitution soon.

"The new Syrian constitution will be put to a referendum within a week or more," he said.

The committee tasked with drafting Syria's new constitution has decided to limit presidential terms to a maximum of two seven-year mandates, Al-Watan newspaper reported on Tuesday.

The paper said the draft constitution would be submitted to Assad in "the coming days" before being put to a referendum.

Late President Hafez al-Assad ruled for five consecutive terms, while the current president is due to complete his second seven-year mandate in 2014.

Tuesday's developments came after Saudi Arabia said on Monday that its observers would be withdrawn.

"Gulf Co-operation Council [GCC] states have decided to follow Saudi Arabia's decision to pull out its observers from the Arab League mission in Syria," the regional bloc said in a statement on Tuesday.

It said the GCC was "certain the bloodshed and killing of innocents would continue, and that the Syrian leadership would not abide by the Arab League's resolutions".

The Syrian Revolution General Commission (SRGC) activist group has said at least 840 Syrians have been killed since December 23, when the first Arab League delegates entered Syria.

Critics say the Arab mission has only provided diplomatic cover for Assad to pursue a crackdown that has already killed more than 5,000 people since protests erupted in March 2011, according to a UN count.

On Tuesday, an activist network reported the death of at least 68 people, of whom 37 were killed in the central province of Homs.

The Local Co-ordination Committees (LCC) activist network said at least 18 people were killed when government forces shelled two buildings in the Homs' neighborhood of Bab Tadmor.

Speaking to Al Jazeera from Homs, Hadi al-Abdallah, an activist with the SRGC, said: "The buildings were six-storey buildings. Many families remain missing. It is hard to confirm the exact number of those killed."

He added that there was an escalation of violence on the part of government forces, especially in Homs' old neighbourhoods.

"Al-Dabi's report speaking of armed groups gave the regime more justification to intensify the killing," he said.

Elsewhere in Syria, activists said security forces resumed their military assult on Hama, mainly in al-Hamidiyeh neighbourhood, and that military tanks were present in most of the city's main streets.

The LCC said at least seven people were killed there.

Despite the violence, several anti-government protests took place across the country on Tuesday evening, activists said.

PHOTO CAPTION

A picture from the Local Coordination Committees of Syria shows the funerals of 12 people allegedly killed in Douma on January 23.

Aljazeera