London's FTSE 100 was lifted by export-focused stocks on Tuesday as uncertainty over whether British lawmakers would support the government's Brexit deal took its toll on the pound. The FTSE 100 added 0.7%, with BP and Shell both gaining more than 2% and Asia-focussed HSBC also rising after China signalled progress in trade talks with the United States.

Other standouts in the index, whose components book most of their earnings abroad, were AstraZeneca and BAT, while Durex condom maker Reckitt pared losses despite cutting its sales view for the second time this year. However, the domestically-focussed FTSE 250, which has gained more than 4% since September on hopes of a smooth end to the Brexit process, slipped 0.5%.

British Prime Minister Boris Johnson told parliament that if it delayed his legislation to leave the European Union he would abandon his attempt to ratify the deal and push for an election instead, threatening further political turmoil. "The optimism of last week about the prospect of a deal being approved has been replaced by a sense of fatigue," David Madden at CMC Markets said.

Just Eat was the stand-out performer in the FTSE 100, surging 24.2% to 732 pence after rejecting an offer by Dutch firm Prosus of 710 pence-a-share offer. "You may need more like 750 pence to sort this out," Markets.com analyst Neil Wilson said, predicting a bidding war.

Just Eat has already accepted a takeover by Takeaway.com, and its shares enjoyed their best day since they floated in April 2014. London-listed shares of travel firm TUI were among the few fallers, dropping 7.3% after Morgan Stanley downgraded the stock and warned concerns around Boeing's 737 MAX aircraft and demand uncertainty could be headwinds. Business supplies distributor Bunzl fell 2.8% to its lowest since February 2016 as its quarterly organic sales growth slowed, while M&G dropped 6.4% on its second day of trading after demerging from Prudential.