By Shadia Nasralla
LONDON (Reuters) - Oil prices slipped on Thursday, extending losses into a second consecutive session following a surprise rise in U.S. crude inventories.
International Brent crude oil futures were at $67.11 a barrel at 1157 GMT, down 72 cents from their last close.
U.S. West Texas Intermediate (WTI) crude futures were at $58.61 per barrel, down 80 cents from their last settlement.
U.S. crude inventories rose last week by 2.8 million barrels, compared with analysts' expectations for a decrease of 1.2 million barrels, the U.S. Energy Information Administration said.
Demand concerns on the back of economic jitters linked to the U.S.-Chinese trade war have also capped prices.
In a fresh development, China made unprecedented proposals on a range of issues, including forced technology transfer, as the two sides work to end their protracted dispute.
Overall, bullish sentiment continues to underpin the market, with Brent rising almost 30 percent this year.
"Today's fall does not derail the short-term bullish argument that both the OPEC+ production cuts and supply outages will outweigh the global growth concerns and rising U.S. production," said Edward Moya, senior market analyst at OANDA.
Oil prices are being supported by efforts by the Organization of the Petroleum Exporting Countries (OPEC) and non-affiliated allies like Russia to trim output, as well as plummeting Venezuelan output.
On top of U.S. sanctions, power cuts have crippled Venezuela's oil industry.
The country's main oil export port of Jose and four crude upgraders, needed to convert Venezuela's heavy oil into exportable grades, have been halted since Monday, industry sources said.
U.S. sanctions have also hit Iranian crude exports.
In early May, analysts expect the United States will extend some sanction waivers on Iranian oil but might reduce the number of countries receiving them.
The 180-day exemptions were granted in November to China, India, Greece, Italy, Taiwan, Japan, Turkey and South Korea.
Washington is seeking to cut Iranian oil exports to zero.
"Enjoy it whilst it lasts. The upcoming six months will bring relatively healthy demand for OPEC oil," PVM's Tamas Varga said in a note.
"If the unplanned supply cuts remain in place... oil prices should edge towards $75/bbl ...in coming months as global inventories will draw."
