LONDON (Reuters) – Oil slid to around $66 a barrel on Thursday, pressured by concerns over whether the G20 summit will produce a breakthrough on trade and perceptions that supply is ample despite the prospect of continued OPEC curbs.

U.S. President Donald Trump said on Wednesday a trade deal with Chinese President Xi Jinping was possible this weekend but he is prepared to impose U.S. tariffs on most remaining Chinese imports if the two countries don’t agree.

“A complete breakdown of the talks will have a negative impact on the financial markets and also on oil, but the sell-off in risky assets should be short-lived,” said Tamas Varga of oil broker PVM.

“Oil bulls might have to wait until the second half of next week to start firing from all cylinders.”

Brent crude, the global benchmark, was down 61 cents at $65.88 by 0840 GMT. U.S. West Texas Intermediate crude fell 35 cents to $59.03.

Oil jumped by more than 2% on Wednesday after the latest U.S. petroleum supply report showed a larger-than-expected drop in crude stocks. Inventories fell 12.8 million barrels, more than the 2.5 million barrel decrease analysts had expected.

Nonetheless, supply remains sufficient in the world’s biggest oil consumer.

“U.S. oil inventories remain well above the five-year average, signaling a well-supplied market,” said Carsten Menke of Swiss bank Julius Baer. “Demand still looks soft, while the supply situation remains fragile.”

Traders said uncertainty over a trade breakthrough at the G20 – which could translate into a stronger oil demand outlook – and doubts about continued output cuts by OPEC and its allies were crimping follow-through buying.

“It would be unwise to be unprepared for a possible scenario where talks descend into disagreements on trade,” said Lukman Otunuga, research analyst at FXTM.

“Such an outcome will most likely rattle financial markets as concerns over slowing global growth and sizzling trade tensions fuel risk aversion.”

After the G20 summit ends on Saturday, the Organization of the Petroleum Exporting Countries (OPEC) and allies including Russia meet on Monday and Tuesday to discuss an extension of production cuts to support prices.

The alliance, known as OPEC+, is widely expected to keep the same level of supply cuts in the second half of 2019, although other outcomes are possible.