U.N. humanitarian aid chief Valerie Amos said on Wednesday she was deeply disappointed that Syria has refused to allow her to the visit the country, where she had hoped to assess the need for emergency relief in besieged towns.

Amos said in a statement that the refusal came despite my repeated requests to meet Syrian officials at the highest level to discuss the humanitarian situation and the need for unhindered access to the people affected by the violence.

Given the rapidly deteriorating humanitarian situation, with an increasing need for medical assistance, food and basic supplies, improving access, so that assistance can reach those in urgent need, is a matter of the highest priority, she said.

A senior Western diplomat said on condition of anonymity that Damascus' refusal to allow Amos into Syria came despite Russian efforts to get her access.

It was not immediately clear what impact Damascus' refusal would have on Russia, which last week encouraged U.N. Secretary-General Ban Ki-moon to send a representative to liaise with all sides for the safe transit of aid convoys.

Russia and China have twice vetoed U.N. Security Council resolutions condemning Syria for its 11-month crackdown on pro-democracy protesters across the country that the United Nations says killed more than 7,500 civilians, saying Western and Arab nations are seeking Libya-style regime change in Syria.

Amos' Office for the Coordination of Humanitarian Affairs plans to organize a humanitarian conference on Syria on March 8 in Geneva, which might include an appeal for aid, envoys said.

The senior diplomat said that Syria clearly did not want Amos to see the violence in Homs and other locations.

U.S. Ambassador to the United Nations Susan Rice said denying Amos access to Syria was shameful.

Rather than meeting the needs of its people, the barbaric Syrian government is preparing its final assault on the city of Homs, she said in a statement.

A senior U.N. official said on Tuesday that government security forces have prevented more than 5,000 civilians from fleeing Syrian towns under siege.

U.S. DRAFTS NEW RESOLUTION

The newly appointed U.N.-Arab League envoy on the Syrian crisis, former U.N. Secretary-General Kofi Annan, will meet with his successor Ban Ki-moon and members of the Security Council this week, Annan and U.N. diplomats said.

Annan, too, hopes to visit Syria soon to meet with Syrian officials, though like Amos he will need Damascus' permission. Annan was appointed after the U.N. General Assembly adopted a resolution this month calling for an envoy to be named to push implementation of an Arab League plan for Assad to step aside.

The United States has drafted an outline for a new Security Council resolution on Syria, this time to demand access for humanitarian aid workers in conflict-torn towns and an end to the violence there, Western envoys said on Tuesday.

Diplomats said that Washington was consulting with Britain, France and other allies, including Arab states, in the drafting process. The senior diplomat said that it was unlikely they would have a text ready to present to the full 15-nation Security Council before Russia's March 4 presidential election.

While the U.S. draft focuses on the humanitarian crisis in Syria, Western diplomats said it would have to make clear that the cause of that crisis is the government's crackdown on protesters opposed to Syrian President Bashar al-Assad.

That, diplomats said, could make it difficult to secure Russian support for the draft. They said China has indicated that it is uncomfortable with the angry reaction its vetoes have provoked in the Middle East and has sought to reassure the Arab League that Beijing remains a strong partner for the Arab world.

Russian Prime Minister Vladimir Putin is widely expected to win the March 4 election and return to the presidency. He has accused NATO of overstepping its U.N. Security Council mandate to protect civilians in Libya and has said that Moscow did not want that repeated in Syria.

A Syrian senior official, speaking in Geneva on Tuesday, indicated that Damascus was prepared to accept some assistance from the United Nations, which has been shut out of the country, leaving the International Committee of the Red Cross as the only international aid agency deploying aid workers there.

Syria welcomes any technical assistance that can be provided by the United Nations to Syrian institutions, Syrian Ambassador to the U.N. in Geneva Faysal Khabbaz Hamoui told an emergency debate on the crisis at the U.N. Human Rights Council before walking angrily out of the meeting hall.

(Additional reporting by Stephanie Ulmer-Nebehay in Geneva; Editing by Jackie Frank and Vicki Allen)