(Reuters) - Oil prices fell further in early Asian trade on Friday, and were on track for the worst week in months over U.S. President Donald Trump's new tariffs, stoking concerns over a global trade war that could weigh on oil demand.

Brent futures fell 31 cents, or 0.4%, to $69.83 a barrel by 0157 GMT. U.S. West Texas Intermediate crude futures were down 32 cents, or 0.5%, to $66.63.Brent was on course for its biggest weekly loss in percentage terms since the week ended October 14, and WTI since the week ended January 21.

Adding to the bearish sentiment was a decision by the Organisation of Petroleum Exporting Countries and their allies (OPEC+) to advance their plan for oil output increases, with the organisation now aiming to return 411,000 barrels per day to the market in May, up from 135,000 bpd as initially planned.

"This brings forward the expected surplus that we see in the oil market this year. More OPEC+ supply should translate to more medium sour crude oil and a wider Brent-Dubai spread," analysts at ING said on Friday. "This spread has seen an unusual discount for much of the year."

Both benchmarks started plunging lower since Trump's news conference on Wednesday afternoon, which he called "Liberation Day" as he announced a 10% baseline tariff on all imports to the United States and higher duties on dozens of the country's biggest trading partners.

Imports of oil, gas and refined products were exempted from Trump's sweeping new tariffs, but the policies could stoke inflation, slow economic growth and intensify trade disputes, weighing on oil prices.