Oil rig
Oil rigReuters File

Crude futures slipped on Tuesday on a persistent global glut and the failure of a producer meeting at the weekend to rein in the ballooning oversupply, although a sharp drop in output in Kuwait due to an oil worker strike underpinned prices briefly.

Kuwait's output has dropped to 1.1 million barrels per day (bpd) from 2.8 million bpd due to the worker strike. However, analysts expect the disruption to be brief and markets to soon refocus on the global glut given the failure of major exporters to agree on an output freeze at their Sunday meet.

Brent crude was at $42.78 a barrel at 0317 GMT, 13 cents below their previous close. U.S. West Texas Intermediate (WTI) futures were down 5 cents at $39.73 a barrel.

The benchmarks had climbed to $43.20 and $40.13, respectively, earlier in the session on Kuwait's output woes.

Kuwaiti officials, however, say they will be able to hike output, despite the open-ended strike, by using crude from inventory and by taking legal action against unions.

According to analysts, the government is also likely to compromise with the strikers to fully resume exports.

"Sensitive to union pressure, the government is likely to compromise on most of striking oil workers' pay demands," policy risk consultancy Eurasia Group said.

"In the coming days oil production is likely to partially recover from its initial drop as non-striking staff is redistributed and inventories drawn upon, avoiding a force majeure on loadings," it added.

Once Kuwait's exports fully resume, traders said the market would again focus on a global glut that sees 1 to 2 million barrels of crude pumped every day in excess of demand.

A deal to freeze oil output by OPEC and non-OPEC producers fell apart on Sunday after Saudi Arabia demanded that Iran join in despite calls on Riyadh to save the agreement and help prop up crude prices.

But analysts have been sceptical of how successful an output freeze would be in the long term with producers such as Saudi Arabia and Russia pumping near record levels.

"It is nearly impossible to influence the oil price long-term by freezing production as unconventional oil and gas and alternative energy may enter the market to bring down the price," said Vivien Yang, partner at law firm Simmons & Simmons in Hong Kong.

"The recent failed OPEC attempt to freeze production may cause grief for oil producers, but in reality even if it was successful its long term effect is doubtful."

Many in the market expect oil prices to stay close to the historical average at around $30 to $40 per barrel, Yang said.