* Brahimi in Moscow Saturday to discuss peace proposals
* World powers divided over Assad's role in transition
* Moscow says Assad's exit cannot be precondition for talks
MOSCOW, Dec 28 (Reuters) - Russia expects to meet senior U.S. officials on Syria next month to discuss with international envoy Lakhdar Brahimi his proposals to end the 21-month-old conflict there, the Kremlin's envoy to the region said on Friday.
Brahimi will fly to Moscow on Saturday for talks on the results of his negotiations with Syrian President Bashar al-Assad and his opponents during a five-day trip to Damascus in which he called for political change to end the bloodshed.
"We will listen to what Lakhdar Brahimi has to say about the situation in Syria and after that, probably, there will be a decision to hold a new meeting of the 'three Bs'," Russian Deputy Foreign Minister Mikahil Bogdanov said - making a word play on the first letter of the diplomats' last names.
Bogdanov, U.S. Undersecretary of State William Burns and Brahimi, the joint special representative of the United Nations and the Arab League, agreed that a political solution to the crisis was necessary and possible in talks earlier this month.
Bogdanov said another meeting of the three "will take place already in January after the holidays."
Brahimi, who has called for a transitional government to rule until elections, is trying to broker a peaceful transfer of power in Syria, where more than 44,000 people have been killed in a revolt against four decades of Assad family rule.
What role Assad and members of his government might play in a transitional body - a plan outlined in an international agreement in Geneva six months ago - has divided world powers.
Past peace efforts have floundered as what began as peaceful protests in March 2011 has turned to civil war and an increasingly sectarian struggle between mostly Sunni Muslim rebels and Assad's security forces, drawn primarily from his Shi'ite-rooted Alawite minority.
World powers believe Russia, which has given Assad military and diplomatic aid to help him weather the uprising, has the ear of Syria's government and must be a central player in any peace talks.
Moscow has tried to distance itself from Assad in recent months and has said it is not propping him up, but it maintains Assad's exit from power cannot be a precondition to talks.
On Thursday, Russian Foreign Minister Sergey Lavrov warned that time was running out to find a peaceful solution to the conflict and halt a descent into "bloody chaos," during a meeting with Syrian Deputy Foreign Minister Faisal Makdad in Moscow.