Apparent daily appetite for refined copper in China, the world's top consumer, grew 5 percent in May from April, Reuters calculations show, as a fall in imports was offset by rising output and a drop in stock levels.

Copper consumption came in at just over 700,000 tonnes last month, versus 650,000 in April.

China's arrivals of refined copper fell 9.7 percent in May from last month in their second straight monthly drop, while on a daily basis, accounting for the longer May month, imports fell almost 13 percent.

In May, China, the world's top copper consumer, imported 279,690 tonnes of refined copper, the most popular type of copper in Chinese and international markets, data from the General Administration of Customs showed on Monday.

The May inflow was down from 309,772 tonnes in April which was a fall of 8.1 percent from March, and below expectations of 290,000 to 300,000 tonnes.

Import demand for spot refined copper increased last month as a favourable arbitrage opened between London and Shanghai prices, traders said.

About 100,000 tonnes of bonded copper already in Shanghai filled much of that extra demand, driving up premiums for bonded copper in Shanghai to $110-$120 per tonne over cash LME copper prices in early June from $80-$100 a month earlier.

Last month Chinese buyers also placed spot orders for more than 10,000 tonnes of Chilean refined copper, which would start arriving in late June, with the bulk to land in Chinese ports in July.

Beijing's measures to cool the property sector, the major user of base metals, had made buyers cautious, Lan Ke, analyst at the assets management division at Southwest Securities, said.

"People had expected prices to fall," he added. But he noticed that the expectation was changing after China's central banks said over the weekend that the world's top consumer of most base metals would gradually make the yuan's exchange range more flexible.

The statement strongly suggested that China was ready to break the currency's 23-month-old dollar peg, which quickly pushed up yuan against the U.S. dollar to 21-month high on Monday and drove up metal prices.

Imports of primary aluminium from China, the world's biggest consumer and producer of the metal, dropped 3.2 percent on the month to 28,045 tonnes in May due to the delay and cancellation of contracted shipments last month on the fall in LME aluminium prices.

Exports of primary aluminium dived 48 percent on the month to 25,265 tonnes in May on reduced supply of bonded stocks, the main source for a 16-month outflow high in April that made China a net exporter of the metal for the first time since 2008.

But imports of refined lead jumped to 3,144 tonnes in May, up from 260 tonnes in April, due to weak LME prices.