DUBAI, Sept 6 (Reuters) - Gulf stock markets may rise on Tuesday after Saudi Arabia and Russia said they would cooperate to support oil prices, but any gains look likely to be minor because of scepticism about the deal.

Brent crude futures jumped almost 5 percent late on Monday afternoon before a news conference at which the two countries announced their agreement, but by Tuesday morning they have given up most of those gains, standing at $47.71 a barrel.

The two countries did not announce specific steps and many analysts think it would be difficult for them to join with other big oil producers to restrain output, and that even if they agreed on action, it might not do much to boost prices.

Riyadh's stock index rose 1.7 percent to 6,204 points on Monday as oil climbed, so it may have little further to rise for now. The index faces technical resistance at 6,226-6,257 points, the lows in early August and June.

Other Gulf bourses closed on Monday before oil took off, so they may have more room to rise; MSCI's broadest index of Asia-Pacific shares outside Japan is up 0.5 percent.

Dubai- and Cairo-listed Orascom Construction's board of directors approved a proposal to buy back up to 1 million Cairo-listed shares, but that is a tiny fraction of the stock's free float of 50.8 million shares.

(Editing by Andrew Torchia) ((celine.aswad@thomsonreuters.com; +971 4 4536886; Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))