China's surging steel exports, the source of growing friction with its trade partners, rose 77 percent in May, according to government figures reported Thursday.

Exports of rolled steel totaled 6.2 million tons, the official Xinhua News Agency said, citing the customs agency. It said exports in May were a decline of 13.8 percent from April but a 77 percent increase over the same month last year.

Beijing has been trying to rein in steel exports to ease tensions with trading partners whose own steelmakers are struggling against a flood of low-cost Chinese imports. Chinese leaders also worry about the industry's rising energy demands and environmental impact.

The government has eliminated rebates and imposed a new tax on exports to discourage foreign sales.

Exporters probably rushed to ship as much steel as they could to beat the new export duty, which took effect June 1, Xinhua said, citing the Commerce Ministry.

Steel exports for the first five months of the year totaled 27.5 million tons, up 117 percent from the year-earlier period, Xinhua said.