Oil markets were little changed on Friday, supported by ongoing supply cuts and strong demand, although the prospect of rising US shale output capped prices around recent gains.

Brent crude futures LCOc1 were at $63.80 per barrel at 0252 GMT, down 13 cents from their last close, but still within $1 of a more than two-year high of $64.65 a barrel reached earlier this week.

US West Texas Intermediate (WTI) crude CLc1 was at $57.02 per barrel, down 15 cents but also not far from this week?s more than two-year peak of $57.92 a barrel.

Analysts said the high prices were a result of efforts by the Organization of the Petroleum Exporting Countries (OPEC) and Russia to withhold supplies to tighten the market, as well as strong demand and rising political tensions.

?Oil prices have rallied sharply over the past week ... The latest catalyst for this move higher was the sharp rise in geopolitical tensions last weekend, with growing confidence in an OPEC extension and strong oil demand fuelling the rally previously,? said US bank Goldman Sachs.

But there were some words of caution. ?This (oil upward) move may be short-lived as ... it is possible that shale ... production can be brought back on stream relatively quickly,? said Goldman?s peer Morgan Stanley.

Goldman warned of greater price volatility ahead due to increasing tensions in the Middle East, especially between OPEC fellows but political arch-rivals Saudi Arabia and Iran, along with soaring US oil production.

?We see potential for high spot price volatility in the coming weeks,? Goldman said.

?A rise in the US rig count and a non-committal OPEC meeting would push prices lower, in our view, yet additional escalation of recent geopolitical tensions could lead to another large rally,? it added.

ANZ bank said that ?political stability was jolted awake this week? in the Middle East.

?While the likelihood of a disruption to (oil) supply remains low, we believe the events raise the probability of Saudi Arabia taking a more aggressive stance on production curbs ... As such, we see oil prices remaining well supported in the short term,? ANZ said.

OPEC is due to discuss output policy during a meeting on Nov. 30, and it is expected it will extend the cuts beyond the current expiry date in March 2018.

?Recent OPEC communication suggests that an extension will be announced but there are no details on volumes,? Goldman said.