* Oil falls as low as $118, lowest since May 5
* Concern of weakening demand pressures oil, commodities
* Iran dispute, Nigeria conflicts lend support
(Adds details, updates prices)
By Alex Lawler
LONDON, Aug 5 (Reuters) - Oil fell to $118 a barrel on Tuesday, a three-month low, as investors focused on rising OPEC supply and declining demand in the United States and Europe.
The loss extends a slide from the July 11 record high of $147.27 a barrel and has prompted some to say that oil's rally has run its course for now.
"Most of the hedge funds have been taking profits," said Angus McPhail of British-based investment firm Alliance Trust.
Asked how far prices could fall, he said: "Probably to about $100 within the next month if you keep on getting weak demand data."
U.S. crude <CLc1> was down $1.83 at $119.58 a barrel by 1515 GMT, up from a session low of $118.00, the lowest price since May 5. London Brent crude <LCOc1> lost $2.26 to $118.42.
Other commodities such as copper, gold and platinum also fell, hit by expectations slower economic growth would limit demand and as the dollar rose, making commodities priced in dollars more expensive for holders of other currencies.
The dollar rose to a six-week high as investors awaited the outcome of a Federal Reserve meeting later in the day. The Fed is expected to leave its benchmark interest rate at 2.0 percent as it faces higher inflation risks and threats to economic growth.
Potentially bullish factors for the oil price included Tropical Storm Edouard, which has curbed Gulf of Mexico oil production, shipping and refining. But traders were discounting the risk of wider disruption to oil facilities.
"It seems that the market is losing interest in geopolitical and weather-induced 'props', and instead is becoming more aware of growing supply/demand imbalances," said Edward Meir, analyst at MF Global.
Tension between major oil exporter Iran and the West over Tehran's nuclear work, and supply losses and violence in Africa's top producer Nigeria, also provided some support for oil prices.
Iran has handed European Union officials its written reply to a proposal backed by six world powers aimed at defusing a row over the nuclear programme, Iran's Fars News Agency said on Tuesday.
Technical analysts, who base price predictions on analysis on previous movements, have said that in the near term prices could find support around $115 a barrel.
Some have said the market could fall as far as $60 a barrel before the long-term bull trend is finally extinguished. (Additional reporting by Seng Li Peng in Singapore and Barbara Lewis in London; editing by William Hardy)