UPDATE 4-OPEC and allies agree to deepen oil output cuts

Rania El Gamal, Shadia Nasralla and Alex Lawler

* OPEC+ panel recommends additional cuts of 500,000 bpd

* Oil glut looms due to booming output in U.S., Brazil, Norway

* No clarity yet on how long cuts will last

* Russia says new cuts will last until Q1, OPEC wants more (Updates with Novak)

VIENNA, Dec 5 (Reuters) - OPEC and allies led by Russia on Thursday agreed one of the deepest output cuts this decade to support crude prices and prevent a glut but were still debating how long the curbs would last next year.

The Organization of the Petroleum Exporting Countries (OPEC) is meeting to discuss supply policy in Vienna. OPEC will then meet on Friday with Russia and other producers, a grouping known as OPEC+.

Russian Energy Minister Alexander Novak said a panel of key energy ministers including Saudi Arabia and Russia had recommended the OPEC+ group deepens existing supply curbs of 1.2 million barrels per day by another 500,000 bpd. The cut of 1.7 million bpd would amount to 1.7% of global supply.

He said cuts would last through the first quarter of 2020, a much shorter timeframe than suggested by some OPEC ministers, who have called for extending cuts until June or December 2020. OPEC could in theory decide to approve a longer timeframe than OPEC+.

"We concluded that in order to safely go through the seasonal demand period in the first quarter of 2020 it could be recommended that countries additionally cut up to 500,000 barrels per day," Novak said.

OPEC+ has agreed voluntary supply cuts since 2017 to counter booming output from the shale fields of the United States, which has become the world's biggest producer. Washington has forced an even steeper reduction in supply through sanctions on OPEC members Iran and Venezuela aimed at choking both countries' oil export revenue.

As producers meet on Thursday and Friday they will consider how to balance their supply with another year of rising output from the United States in 2020. Other non-OPEC countries such as Brazil and Norway are also expected to pump more oil.

Ministers from Saudi Arabia, Russia, Kuwait, the UAE, Algeria, Oman and Algeria had their pre-OPEC meeting on Thursday with the OPEC meeting still not started as of 1520 GMT.

For a timeline of OPEC cuts


Saudi Arabia needs higher oil prices to support its budget revenue and the pending initial public offering (IPO) of state-owned oil giant Saudi Aramco with pricing of the IPO expected on Thursday.

OPEC's actions in the past have angered U.S. President Donald Trump, but Trump has said little about OPEC in recent months. That might change if oil and gasoline prices rise ahead of the U.S. presidential election set for November 2020.

OPEC's actions have supported oil prices at around $50-$75 per barrel over the past year. Brent crude futures on Thursday extended this week's gains to trade above $63 per barrel.

OPEC sources have said Riyadh was pressing fellow members Iraq and Nigeria to improve their compliance with quotas, which could provide an additional reduction of up to 400,000 bpd.

(Reporting by Bozorgmehr Sharafedin and Olesya Astakhova; writing by Dmitry Zhdannikov; editing by Jason Neely and Simon Webb)