Crude oil prices have plunged after Iran and world powers announced a press conference following months of talks about Iran's nuclear programme.
Iran and the European Union are expected to read a joint statement at 18:00 BST on Thursday, although it is not clear whether the statement will include tangible facts about the content of the deal.
Iranian foreign minister Mohammad Javad Zarif is expected to hold a press conference afterwards, as is US Secretary of State John Kerry.
A nuclear deal could remove Western sanctions imposed on Iran and lead to millions of barrels of Iranian oil coming on to the market.
Benchmark Brent crude was trading down by 4.06% at $54.78 a barrel at 17:06 BST while WTI Crude was down 2.34% at $48.92 a barrel.