UNITED NATIONS, : The United Nations on Thursday sent its top military official to Syria to take charge of an observer mission as the UN Security Council wrangled over the future of the operation.

Because of the growing dangers in Syria, European nations on the council have proposed giving the unarmed observers a final 30-day mandate to let it be closed.

A Security Council vote could be held Friday, diplomats said.

General Babacar Gaye, chief UN military adviser, was earlier sent to Damascus, UN Deputy Secretary General Jan Eliasson told reporters.

He added that UN peacekeeping chief Herve Ladsous would also be going to the Syrian capital in coming days.

The mandate of the UN Supervision Mission in Syria (UNSMIS), made up of nearly 300 unarmed military observers and 100 civilian staff, ends on Friday.

Its leader Major General Robert Mood of Norway is due to leave the same day.

If the Security Council cannot agree to extend the mandate, the mission would have to be quickly closed, UN officials said.

Gaye, of Senegal, would oversee the closure if that was decided or take temporary charge of any extended operation.

The observers were sent to monitor a ceasefire, that was agreed in April but never took hold. They suspended their operations on June 16 because of the mounting violence.

Eliasson said the situation in Syria was “dramatic and dangerous” and that the UN leadership was acting while waiting for the Security Council’s decision.

“It is a fluid situation but we wanted to make sure that we have a strong leadership in place. We will then be guided by what the Security Council has decided,” he added.

“If we can play a meaningful role with UNSMIS and its possible continuation we will do so. But we will of course also watch the security situation extremely carefully. We have had traumatic experiences at the UN in the past.”

Russia and China vetoed a Security Council resolution proposed by European nations and the United States that called for the threat of sanctions against the Syrian government to be added to the renewal of the UN mission.

Britain has since proposed a new resolution that would give UNSMIS another 30 days in Syria.

Pakistan said it would also propose a technical extension of the mission.

The United States has expressed new skepticism about keeping the observers in Syria after the veto of any threat of sanctions.

“A rollover of the UN mission without it being tied to the potential for consequences for non-compliance or improvement in conditions on the ground does not make any sense,” US Ambassador Susan Rice told reporters. “We might consider a final brief extension of the mission, should that be proposed, if it would allow for the monitors and civilian staff to withdraw safely.”

Russia's Ambassador Vitaly Churkin said he expected a vote on a resolution on UNSMIS on Friday.