Mumbai: China's trade surplus almost doubled in the first quarter of the current year – rising to $46.4 billion from $23.3 billion a year earlier – forcing the United States to move the World Trade Organisation (WTO) against its second-largest trading partner.

The US moved the World Trade Organisation against Beijing for piracy and blocking access for US films, books and software.

Washington has charged Bejing with violation of breaking its 2001 WTO entry agreement and sought consultations with Beijing over the twin complaints, which could lead to a formal case being brought if no deal can be struck within 60 days.

The surplus widened to $6.87 billion in March, the customs bureau said on its web site.

The US allegations of copyright violations come 10 days after it imposed duties on imports of Chinese coated paper. US lawmakers say China uses an undervalued currency and subsidies to help spur the nation's booming exports of textiles, electronics and toys.

The US move follows congressional concerns over last year's record US trade deficit with China hampers efforts to win renewal of trade promotion authority, which the White House needs to finish negotiations on the WTO's Doha round of trade talks.

China said it regretted the decision and warned that it could seriously damage cooperation and hurt bilateral trade.

Schwab said that action should not be viewed as hostile and denied the two countries risked slipping into a trade war.

Washington remained open to a negotiated settlement without going through the WTO, which could take 18 months or more, she added.

China's trade surplus swelled to a record $177.5 billion last year, helping to fuel a 10.7 per cent economic growth, the fastest since 1995. Exports gained 6.9 per cent to $83.4 billion in March, the slowest pace in five years, and imports climbed 14.5 per cent to $76.6 billion.

The yuan has gained 7 per cent versus the US currency since a fixed rate was scrapped in July 2005. It was little changed at 7.7350 against the dollar at 5:30 p.m. in Shanghai.