UNITED NATIONS - The UN Security Council has scheduled a vote on a draft resolution on Saturday to authorize the deployment to Syria of up to 300 unarmed military observers, despite US and European concerns that Damascus has yet to fully implement a ceasefire.The United Nations announced on Friday the 15-nation council planned to hold the vote at 11:00 a.m. EDT (1500 GMT). It will be considering a compromise resolution that combines Russian and European drafts.There are seven monitors already in Syria from Morocco, Brazil, Belgium, Switzerland and Norway after the council authorized an advance team of up to 30 on Saturday. A new resolution is needed for a further "initial deployment" of up to 300 as recommended by UN Secretary-General Ban Ki-moon.Some council members have expressed reluctance to give swift approval for an expanded observer mission because of concern about the failure of the Syrian government to halt the violence, return troops to barracks and withdraw heavy weapons.At least 23 people were killed on Friday, 10 of them by a roadside bomb targeting security forces and most of the others in shelling by President Bashar Assad's forces on the city of Homs, further undermining the truce.The draft resolution calls for authorizing the deployment of 300 unarmed observers for an initial three-month period and urges Syria to implement its pledges under a six-point plan drawn up by UN-Arab League mediator Kofi Annan.Draft warns of "further steps"The United States and European countries have insisted that Syria must accept the use of UN planes and helicopters by the UN mission, which will be called UNSMIS.The Russian draft resolution did not mention air assets and was less critical of Syria's government than the European text. The compromise draft urges Syria to reach an agreement with the UN on "appropriate air transportation assets" and condemns the government for "widespread violations of human rights."Syria has dismissed any need for UN aircraft. The UN's Ban has said helicopters and other military hardware would be needed by the monitors.The European draft had threatened Syria with sanctions if it did not end violence by Syrian troops. The Russian draft did not include the threat of sanctions.The compromise draft, also obtained by Reuters, warns Syria of possible "further steps" if it does not comply with the resolution. It does not specify what those steps would be.It calls for Ban to report back to the council on Syria's compliance within 15 days.Moscow has accused the United States and Europe of tricking it into using a UN mandate to protect civilians in Libya to enable NATO to engage in "regime change." Syria's ally Russia, along with China, support Assad and have twice vetoed council resolutions condemning has assault on pro-democracy protesters.But last week Russia and China joined the rest of the council in voting for a resolution to authorize the deployment of the first batch of UN monitors.The United States has voiced concern over approving an expanded UN mission before Assad fully complies with demands to halt the violence and pull back troops and heavy weapons."We want to see monitors be able to get in. But they've got to be able to do so in the permissive conditions," State Department spokeswoman Victoria Nuland told reporters on Friday, saying the United States had "extreme concerns" about the continued violence."It's got to be a true independent international monitoring effort ... and not regime-controlled," she said.Annan's peace plan calls for an end to fighting by government security forces and rebels, withdrawal of heavy weapons from towns, the return of the army to barracks, humanitarian access and dialogue between the government and opposition aimed at a "political transition."Council envoys reached a preliminary agreement on a draft resolution on the Syrian conflict, a crisis that has left the council divided since it erupted 13 months ago. But there was a possibility the deal could fall through since council members must seek final approval from their capitals overnight."It's possible not everybody will have instructions at that point (11:00 a.m.)," US Ambassador to the United Nations Susan Rice, president of the Security Council this month, told reporters. "It's possible there will not be an agreed text at that point, we'll see, and we'll regroup accordingly."Britain, France and Russia would also like a deal."I hope there's going to be a unanimous vote tomorrow," said Russian Ambassador Vitaly Churkin. "The Syrian government and the opposition must know that the Security Council will be authorizing the full-fledged mandate so we hope it's going to send a strong and good political signal."