UPDATE 6-Oil prices steady as OPEC ministers discuss supply cut pact

* OPEC-led supply pact due to expire in March

* Russian minister: No extension decision till Jan

* Russian minister calls for continued cooperation

* Oil ministers say supply cuts reducing inventories (Updates prices, adds OPEC comments & quotes)

LONDON, Sept 22 (Reuters) - Oil prices were steady on Friday, as investors waited to see whether major producers meeting in Vienna would back an extension to output cuts beyond March next year.

Brent crude futures were up 28 cents at $56.71 a barrel at 1351 GMT, their highest since March.

U.S. West Texas Intermediate (WTI) crude futures were down 2 cents, at $50.53 per barrel.

Some ministers from the Organization of the Petroleum Exporting Countries, Russia and other producers were meeting in Vienna to discuss their deal to cut supplies that runs to March.

OPEC and its allies have been considering extending the deal beyond the end of March.

Russian Energy Minister Alexander Novak said OPEC and other oil producers would not take a decision until January, while other ministers suggested a decision could come this year.

"I believe that January is the earliest date when we can actually, credibly speak about the state of the market," he said, emphasizing that OPEC and other major producers needed to work together on a strategy from April 2018.

Oil prices have gained more than 15 percent in the past three months to trade above $56 a barrel, suggesting the deal is making progress in getting rid of excess supply

Kuwaiti Oil Minister Essam al-Marzouq, who chaired Friday's meeting, said that since the supply cuts "the oil market had markedly improved ... and is evidently well on its way towards rebalancing."

Nigeria and Libya, which have been exempt from the curbs, were also invited to attend the talks.

Despite the current output restraints, increasing U.S. oil production has curbed price gains. Hurricanes in the Gulf of Mexico have also pushed up crude inventories as some U.S. refineries have been shut by flooding.

The Energy Information Administration (EIA) on Wednesday reported U.S. crude production rose to 9.51 million barrels per day (bpd) in the week ended Sept. 15 from 8.78 million bpd a week earlier.

Commerzbank said in a note oil prices were finding some support from tensions sparked by plans by the regional government of Iraqi Kurdistan to hold an independence referendum.

Iraq's government and Western powers oppose holding such a vote in the oil producing region. (Reporting by Fanny Potkin in London and Jane Chung in Seoul; Editing by Edmund Blair and Mark Potter)