BEIJING -- China's exports declined 2.8 percent year on year to 1.17 trillion yuan ($191.16 billion) in May, marking marginal improvement from the previous month but continued pressure on the economy.

Imports slumped 18.1 percent from a year ago to 803.33 billion yuan, bringing trade surplus to 366.8 billion yuan, up a substantial 65 percent, data from the General Administration of Customs (GAC) showed on Monday.

In the meantime, total foreign trade slipped 9.7 percent from a year earlier to 1.97 trillion yuan.

In the Jan-May period, the country's exports increased 0.8 percent and imports decreased 17.2 percent year on year, with foreign trade volume down 7.8 percent, data showed.

Trade surplus in the first five months doubled to 1.33 trillion yuan, the GAC said.

China's trade with the European Union, its biggest trade partner, waned by 7.1 percent during the Jan-May, but that with the United States, the second largest, rose 2.8 percent.

Trade with the Association of Southeast Asian Nations edged down 0.5 percent, while China-Japan trade plummeted by 11.2 percent during this period.

The data also showed China bought more bulk commodities of crude oil and grain in the first five months, but the imports of iron ore, coal and refined oil products shrank, with prices of major goods down.

The imports of oil increased 4 percent year on year to 134 million tons and the iron ore lost 1.1 percent to 378 million tons.