* Fed may cut stimulus as U.S. economy improves - Fed officials
* US crude inventories may have risen 100,000 barrels last week - poll
* Coming up: API weekly inventories data; 2130 GMT
SINGAPORE, Nov 19 (Reuters) - Brent slipped below $108 a barrel on Tuesday as renewed concern about the possible tightening of monetary policy in the United States offset support from continuing oil supply disruption in Libya.
U.S. crude futures posted their biggest daily loss in nearly a week on Monday after top Fed officials pointed to improvements in the U.S. economy that could spur the central bank to start "tapering" its asset purchases.
Comments from incoming Fed chief Janet Yellen last week had suggested the central bank would continue with its ultra-loose monetary policy for some time.
January Brent crude fell 48 cents to $107.99 a barrel by 0602 GMT, down for the third straight session. U.S. crude for December edged down 25 cents to $92.78.
However, Brent remained supported to some extent by Yellen's comments, which had soothed fears of an imminent unwinding of the Fed's $85 billion-a-month stimulus programme, said Yusuke Seta, a commodity sales manager at Newedge Japan. Many in the markets do not expect any change until March.
The lack of a deal between major powers and Iran over its nuclear policy plus supply disruptions in Libya also supported Brent, Seta said.
"When we look at the Western conflict with Iran, it's deeply rooted and not easy to resolve. That's why Brent's January/February spread is steady at about 50 cents a barrel," he said.
The Western countries and Iran will meet from Wednesday to try to forge an interim deal on Tehran's nuclear programme.
Sanctions on Iran have kept around 1 million barrels per day (bpd) of oil from the global market and any deal could allow some of that oil to be sold, depressing a market that is already well supplied.
In Libya, fighting between rival militias and industrial unrest have spread across the country, causing its crude exports to fall by more than 1 million bpd over the past six months.
The price gap between West Texas Intermediate (WTI) and Brent may widen to $15 this week if U.S. oil data showed higher inventories, Newedge's Seta said.
"WTI is leading the crude market downwards because production in the U.S. is increasing steadily and inventories in Cushing are rising," he said.
U.S. crude inventories were forecast to have increased by 100,000 barrels last week, while gasoline supply grew by 200,000 barrels, according to a Reuters poll.
Industry group the American Petroleum Institute will release its weekly data later on Tuesday while the U.S. Energy Information Administration will report its data on Wednesday.
(Reporting by Florence Tan; Editing by Alan Raybould)