* Forecasts for US crude stocks to gain 1.8 mln barrels
* U.S. GDP data eyed for clues on Fed's stimulus plans
* New Libya unrest, Egypt tensions support oil prices
NEW YORK, Nov 5 (Reuters) - U.S. crude oil futures hit a fresh four-month low on Tuesday, pressured by forecasts for rising supplies and continued weak demand as Gulf Coast refineries were expected to remain offline at least through the end of this week.
U.S. crude has fallen in five out of the past six sessions. Brent crude oil fell on Tuesday after hitting a four-month low the previous session.
A steady build in U.S. oil stocks has kept prices under pressure in recent weeks. Data is expected to show a new weekly increase of around 1.8 million barrels, according to a Reuters poll ahead of reports from industry group the American Petroleum Institute (API) and the Energy Information Administration (EIA).
Stocks at Cushing, Oklahoma, the delivery point for U.S. benchmark futures, rose by more than 2 million barrels, the largest build since December 2012, in the week ending Oct. 25.
"North America is creating an avalanche of oil that doesn't seem to have a home right now," said Gene McGillian, an analyst at Tradition Energy in Stamford, Illinois.
"Until the refineries start to ramp back up and make some products that can be shipped out of the country, we'll continue to look for the bottom."
Brent crude fell 78 cents to $105.45 a barrel by 1:06 p.m. EST (1806 GMT) after hitting a four-month low of $105.13 overnight. U.S. oil fell $1.33 to $93.29 a barrel, after posting a fresh four-month low of $93.07.
The U.S. dollar was trading 0.2 percent higher against a basket of currencies as the euro fell and a Tuesday report from the Institute for Supply Management (ISM) showed U.S. service-sector business activity picked up in October, which could strengthen the case for the Federal Reserve to start scaling back stimulus later this year.
"I think the ISM number would suggest more tapering from the Fed," said Phil Flynn, an analyst at the Price Futures Group in Chicago, Illinois.
"Do you really want to be long oil as you're facing potential record supplies, uncertain demand and a higher dollar?"
Investors are looking for important data from the U.S. later this week, including gross domestic product (GDP) and payrolls numbers, to offer a clearer view of the outlook for demand in the world's biggest oil consumer.
The data could also give clues on when the Fed may start to roll back its monetary stimulus, which would reduce the supply of dollars and make dollar-denominated assets such as oil more expensive for holders of other currencies.
Comments by top Fed officials overnight suggested that a cut-back in the stimulus was not imminent.
Renewed tensions in Libya and Egypt offered some support to prices.
Heavy shooting erupted early on Tuesday in Tripoli, the latest unrest in the OPEC producer that highlights the government's inability to control militia groups.
Recent protests and strikes at ports and oilfields had already knocked Libyan crude production down to some 10 percent of its capacity of 1.25 million barrels a day.
The government has been trying to reopen eastern oil ports and fields blocked since summer by militias and tribes demanding a greater share of power and oil wealth.
Tensions in Egypt, where ousted president Mohamed Mursi went on trial and could face a death sentence, also supported oil.
(Additional reporting by Jeanine Prezioso, Ron Bousso and Manash Goswami; Editing by Jane Baird, Keiron Henderson, Chris Reese and Bob Burgdorfer)