Both the FTSE 100 and the FTSE 250 surged almost 1% by 0740 GMT.

Appetite for risky assets soared after President Donald Trump on Saturday offered concessions to China's Xi Jinping at the G20 summit, including holding off slapping new tariffs on goods and relaxing restrictions on tech firm Huawei.

Beijing, in turn, agreed to make new purchases of U.S. farm products as part of renewed negotiations.

Investors piled into equities, especially those of banks with a big presence in Asia such as HSBC and Prudential . Shares of miners, sensitive to news surrounding top metals consumer China, also boosted the main index.

But with no deadline set for the deal and few details on how the parties would resolve key differences that caused previous negotiations to stall, analysts took a cautious stance on the weekend's trade-related developments.

"In the big picture, it doesn't change anything," said Andrew Milligan, head of global strategy at Aberdeen Standard Investments.

"It (G20 meeting) was never likely to solve the whole problem, but it's a useful stepping stone."

Demand for commodities such as gold waned as investors flocked to stocks and the U.S. dollar, leading to a more than 2% drop in the shares of precious metals miner Fresnillo.

"So the can was kicked down the road... but much more work to do on the details of a future stickable agreement," Raymond James analyst Chris Bailey said.

Oil majors Shell and BP advanced as crude prices surged after top producers Saudi Arabia, Russia and Iraq backed a plan to extend supply cuts for another six to nine months.

In one of the few news-driven moves, media services firm Future Plc climbed nearly 12% on the mid-cap index after it forecast full-year results to be ahead of expectations due to growth in media revenue.