Oil prices declined on Friday after three straight days of gains, as gloomy economic growth forecasts renewed concerns over the outlook for demand.

Brent crude LCOc1 was down 36 cents, or 0.6%, at $61.31 by 0318 GMT, Reuters said.

Having risen nearly 1% on Thursday, the global benchmark was still set for a weekly gain of more than 3%.

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West Texas Intermediate (WTI) crude CLc1 was down 35 cents, or 0.6%, at $55.88. The U.S. benchmark rose 0.5% in the previous session and was on track for a weekly gain of 4%.

The strong weekly rise was underpinned by a surprise decline in U.S. inventories of crude and optimism about more efforts to support prices by OPEC and its allies.

Yet, concerns over weakening economic growth remained the fundamental driver for prices.

Economists in a Reuters poll said a steeper decline in global economic growth remains more likely than a synchronised recovery, even as multiple central banks dole out rounds of monetary easing.

Thursday's oil price rally was driven by data showing U.S. inventories dropped by 1.7 million barrels last week, shattering analysts' expectations for an increase of 2.2 million barrels.

Adding further support to prices, Organization of the Petroleum Exporting Countries (OPEC) officials said extended supply curbs are an option to offset the weaker demand outlook in 2020.

Saudi Arabia, OPEC's de facto leader, wants to focus first on boosting adherence to the group's production-reduction pact with Russia and other non-members, an alliance known as OPEC+, before committing to more cuts, sources told Reuters.