(BBC) -- The Arab League is to ask the United Nations Security Council to back its plan to end the violence in Syria.

On Sunday, the League called for the Syrian president, Bashar al-Assad, to step down and hand power to his deputy.

The organisation's chief Nabil al-Arabi and the Qatari prime minister are to travel to New York on Saturday to seek support for its proposals.

Meanwhile, UN human rights chief Navi Pillay said it could not keep track of the death toll in Syria's unrest.

Mr Arabi said he and Sheikh Hamad bin Jassim Al-Thani were to "hold a meeting with the UN Security Council on Monday to seek ratification of the Arab League decision on Syria".

The Syrian government has already rejected the plan, calling it "flagrant interference" in Syria's internal affairs.

It says it is fighting "terrorists and armed gangs" and claims that some 2,000 members of the security forces have been killed.

Some 5,000 people have died since the crackdown which began last March, the UN says.

Ms Pillay said this had risen but added: "We are experiencing difficulties because of the fragmentation on the ground.

"Some areas are totally closed such as parts of Homs, so we are unable to update that figure," she said following a meeting with Security Council ambassadors.

On Wednesday, Russia said it would consider "constructive proposals" to end the the violence but was opposed the use of force or sanctions against its Syrian ally.

Russia and China have already vetoed one resolution condemning the crackdown by the Syrian government.

Diplomats say European and Arab governments are drafting a new text they hope to put to a vote in the Security Council early next week.

On Thursday, security forces launched an offensive against the town of Douma, days after pulling out following intense clashes with anti-regime fighters.

It came came two days after Syrian Foreign Minister Walid al-Moallem said his government would continue with the "security solution" to end the crisis.