Shell and BP climbed about 1% on a surge in crude prices. Broader gains were fuelled by hopes of an end to the stand-off between the world's largest economies, with US President Donald Trump saying his administration had a "very good chance" of making a trade deal with China. Washington is set to host Chinese officials later in the week to further trade talks.
The FTSE 250 missed out, however, ending 0.3% lower. Losses were led by a 16% plunge in building materials supplier SIG after it said weaker construction activity in the UK would hit annual profit in its core units. SIG's peers Travis Perkins and Howden Joinery lost 2.1% and 3.1%, respectively, making industrials the biggest sector drag on the midcap index.
A dip in the pound, due to fears that sizeable differences remain between Britain and the European Union over a potential Brexit deal, also weighed on domestic stocks. Companies which earn a chunk of their earnings in the greenback, including spirits company Diageo and GlaxoSmithKline, edged higher as a fall in sterling means the value of their earnings go up.
Despite yield curves remaining inverted on UK bonds for the second straight day and the FTSE 100 trading below its 200-day moving average - a key technical support -, market participants pinned their hopes on this week's Sino-US trade talks. "If the world economy does start to slow down, that's a much bigger impetus for China and the US to get a trade deal done," Randeep Somel from M&G Investments' global equities team said.
British Airways owner IAG added 3.1% after saying it carried more passengers last month compared to the year-earlier period. Troubled lender Metro Bank, which was recently demoted from the midcap index, jumped as much as 10% after a report that its founder Vernon Hill was working to take the company private. The stock, which has plummeted nearly 90% this year, closed up 2.2%.