* Brent-WTI spread tightest in nearly 3 months
* Heating oil rise supports U.S. oil price
* OPEC output rises in January from 2-1/2 year low -survey
* Coming up: CFTC COT report at 3:30 p.m. EST
NEW YORK, Jan 31 (Reuters) - Brent oil fell by $1 on Friday, putting it on track for its first monthly loss in four months, under pressure from worries over emerging economies turmoil and weak global stock markets.
U.S. crude also fell as traders took profits ahead of the weekend, although losses were stemmed by rising heating oil futures prices, which gained 1.5 percent on cold-weather demand.
The spread between the two benchmarks fell below $9 for the first time in nearly 3 months.
Brent was headed for its first monthly fall since September under pressure from continued concerns over emerging markets that weighed on world stock markets.
European stocks posted their first monthly loss since August on Friday and the U.S. stock market was on course for the same.
U.S. crude oil gave up Thursday's rally and fell more than $1 earlier in the session, positioning it to the end the month lower.
"The market is under pressure because of weekend profit taking after the rally from the last couple days," said Gene McGillian, analyst at Tradition Energy in Stamford, Connecticut.
Brent crude fell by as much as $1.45 to a session low of $106.55 and was last trading at $107.03 at 1:23 p.m. EST (1823 GMT), after closing 10 cents higher in the previous session. Trade was thin with some Asian markets closed for the Lunar New Year holiday.
U.S. oil shed 19 cents to $98.04.
U.S. crude's discount to Brent was last trading at $9.14 after narrowing to $8.85, the smallest point since Nov. 8.
U.S. February heating oil futures rose 5.8 cents to $3.2750 per gallon. The February contract expires at the end of trading on Friday.
Increases in supply also pressured Brent. OPEC's oil output rose in January from December's 2-1/2-year low, due to a partial recovery in Libyan supply and higher shipments from Iraq and Iran, according to a Reuters survey.
Further weighing on oil was a stronger U.S. dollar, which traded near a 2-week high against a basket of currencies, supported by the U.S. Federal Reserve's plan to keep cutting monetary stimulus and by data released on Thursday showing strong U.S. gross domestic product in the fourth quarter.
A strong greenback usually weighs on commodities such as oil that are priced in the currency.
Analysts said Friday's fall in U.S. crude was evidence that the Fed announcement and strengthening dollar finally caught up with crude prices that had been underpinned by cold weather driving up distillates demand.