December Brent crude oil futures LCOc1 were down 42 cents at $52.72 a barrel by 1100 GMT, below Monday's one-year high at $53.73, but off an intraday low at $52.51, while U.S. futures CLc1 were down 43 cents at $50.92 a barrel.

"Higher production from Libya, Nigeria and Iraq are reducing the odds of such a deal rebalancing the oil market in 2017," Goldman analysts said.

Global benchmark Brent crude futures LCOc1 reached a high of $52.57 a barrel, not far off a one-year high of $52.86 a barrel, by 1207, up 64 cents on Friday's close. U.S. futures CLc1 also gained ground, trading at $50.32, up 51 cents.

Brent LCOc1 traded at $52.11 at 1000 GMT, 40 cents down, after touching $52.84 earlier, two cents below the 2016 high. U.S. oil futures traded as high as $50.74 a barrel, a three and a half month high, before falling by 30 cents to $50.14 a barrel. On Thursday they settled at $50.44 per barrel - the first settlement above $50 since June 23.

U.S. West Texas Intermediate (WTI) crude futures were trading at $49.22 per barrel at 0649 GMT, up 53 cents, or 1.1 percent, from their last settlement. In international oil markets, benchmark Brent crude was trading at $51.38 per barrel, up 51 cents, or 1.0 percent.

December Brent crude futures LCOc1 were last up 42 cents at $50.61 a barrel by 0913 GMT, off a session low of $49.74, while U.S. crude futures CLc1 rose 37 cents to $48.61 a barrel, above the day's low at $47.78.

The November contract for global crude benchmark Brent was up 0.78% at $46.33 while its U.S. counterpart West Texas Intermediate gained 0.58% to hit $44.94.

U.S. West Texas Intermediate (WTI) crude had fallen 38 cents to $45.55 a barrel by 0103 GMT, after rising $1.45, or 3.3 percent, in the previous session. Brent crude futures slipped 43 cents to $46.91 a barrel after closing up $1.46, or 3.2 percent.

Brent crude futures LCOc1 rose 73 cents to $46.62 a barrel by 1052 GMT, having rallied from a session low of $45.74, while U.S. crude prices CLc1 rose 54 cents to $45.02 a barrel.

Brent crude futures were at $46.54 per barrel at 0645 GMT (02:45 a.m. EDT), up 77 cents, or 1.7 percent, from their previous settlement. U.S. crude was up 78 cents, or 1.8 percent, at $43.81 a barrel.