SHANGHAI, June 10 (Reuters) - China's foreign exchange reserves rose $6 billion in May to $3.101 trillion, central bank data showed on Monday.

Economists polled by Reuters had expected the country's reserves, the world's largest, would drop $5 billion to $3.090 trillion due to valuation changes in exchange rates and prices of foreign bonds held by China.

Downward pressure on China's yuan currency intensified last month after an unexpected escalation in Sino-U.S. trade tensions, dashing market hopes that the two sides were nearing a deal.

At the same time, unexpectedly weak economic data for April suggested the world's second-largest economy was still struggling for traction despite a flurry of growth-boosting measures rolled out since last year.

The yuan lost 2.5 percent against the dollar in May, its biggest monthly loss since mid-2018. The central bank intervened late in the month to stem the fall and also set stronger daily fixings.

The value of China's gold reserves rose to $79.83 billion from $78.35 billion at the end of April. (Reporting by Josh Horwitz; Writing by Yawen Chen and John Ruwitch; Editing by Shri Navaratnam)