Oil prices dropped on Thursday amid concerns over the escalating trade battle between the United States and China, despite a surprise fall in U.S. crude stockpiles.

Brent crude oil futures were at $69.91 a barrel by 0600 GMT, down 46 cents, or 0.7 percent, from their previous settlement. They earlier fell more than 1 percent. U.S. West Texas Intermediate (WTI) crude futures were at $61.76 per barrel, down 36 cents, or 0.6 percent, having also declined more than 1 percent earlier, as reported by Reuters.

"The inventory numbers from the U.S. only gave oil a transitory boost. It is going to be all about whether the trade talks today can stop Friday's tariff-geddon," said Jeffrey Halley, senior market analyst at OANDA in Singapore.

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The Sino-U.S. trade war has weighed on oil prices this week as heightened tensions between the world's two biggest economies cloud the global economic outlook. U.S. President Donald Trump said on Wednesday that China "broke the deal" in trade talks with Washington and would face stiff tariffs if no agreement is reached. Higher tariffs are set to take effect on Friday, during Chinese Vice Premier Liu He's two-day visit to Washington from Thursday.

"Oil prices haven't reacted too drastically, meaning the market's largely adopting a wait-and-see attitude," said Peter Lee, an analyst at Fitch Solutions in Singapore.

"But any further marring of the prospect of a potential U.S.-China trade deal, which had been taking on a more positive tone in recent weeks, could very well result in renewed pessimism on global demand growth."

Oil prices have had some support from signs of tighter global supply on the back of production cuts by the Organization of the Petroleum Exporting Countries (OPEC) and its allies, including Russia.

Both the Brent and WTI benchmarks have risen more than 30 percent so far this year. Supplies have also been tightened by U.S. sanctions on OPEC members Venezuela and Iran.

An unexpected drop in U.S. crude inventories also kept oil price declines in check. U.S. crude inventories fell by 4 million barrels in the week to May 3, the Energy Information Administration said on Wednesday.