Brent crude futures edged up in early trade on Thursday as Israeli tanks advanced into Gaza, while US crude futures dipped on the prospect of swelling oil inventories.
Brent crude futures for August delivery rose 8 cents to $85.15 a barrel by 0008 GMT. US West Texas Intermediate crude for June was down 27 cents, or 0.3%, to $81.30 per barrel.
A US federal holiday, Juneteenth, kept trading activity subdued.
Israeli troops, backed by tanks, warplanes and drones, moved farther into the Gaza Strip city of Rafah on Wednesday, killing eight people, residents and Palestinian medics said.
Escalating war in the Middle East supports prices as a wider conflict could disrupt oil supply from the region, according to Reuters.
WTI crude, meanwhile, slipped ahead of the US government's oil inventories report, which was delayed by a day due to the national holiday. The Energy Information Administration is due to release last week's oil stocks data at 11 a.m. EDT (1500 GMT) on Thursday.
An industry report release on Tuesday showed US crude stocks rose by 2.264 million barrels in the week ended June 14, market sources said, citing American Petroleum Institute figures, while gasoline inventories fell.
