This comes as markets weighed the chance of supply disruptions from the Iran-Israel conflict against a United States (US) Federal Reserve rates decision that could weigh on oil demand.

Brent crude futures slipped 49 cents, or 0.6%, to $75.96 a barrel. US West Texas Intermediate crude futures fell 38 cents, or 0.5%, to $74.46 per barrel. 
Both had initially been up 0.3% to 0.5% in early trade. 

US President Donald Trump called on Tuesday for Iran's "unconditional surrender" as the Iran-Israel air war entered a sixth day.

The US military is deploying more fighter aircraft to the region to bolster its forces, three officials said on Tuesday.

Israel is running low on defensive "Arrow" missile interceptors, however, raising concerns about its ability to counter long range ballistic missiles from Iran, the Wall Street Journal said on Wednesday, citing an unidentified US official.

Analysts said the market was largely worried about supply disruptions in the Strait of Hormuz, a conduit for a fifth of the world's seaborne oil.

Iran is Organisation of the Petroleum Exporting Countries' third largest producer, extracting about 3.3 million barrels per day (bpd) of crude oil, but spare capacity among producers in the Organisation of the Petroleum Exporting Countries and its allies can readily cover this.

"Material disruption to Iran's production or export infrastructure would add more upward pressure to prices," Fitch analysts said in a client note.

--Reuters--