A new round of trade negotiations between the United States and China has started in London, with both sides trying to preserve a fragile truce brokered last month.

LONDON, June 9 (Reuters) - Top U.S. and Chinese officials will sit down in London on Monday for talks aimed at defusing the high-stakes trade dispute between the two superpowers that has widened in recent weeks beyond tit-for-tat tariffs to export controls over goods and components critical to global supply chains.

Stock index futures were almost flat on Monday, as investors turned their attention to the U.S.-China trade talks expected to be held later in the day. S&P 500 futures (SPX) +0.1%, Nasdaq 100 futures (US100:IND) +0.