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.

Wall Street's main indexes were set to open higher on Monday as investors watched a fresh round of negotiations between the United States and China aimed at mending a trade rift that has rattled financial markets for much of the year.