The US and China discussed trade and business concerns Thursday -- with currencies and property rights among the thorny issues on the agenda -- as the world's two biggest economies held wide-ranging annual talks.

"China and the United represent the greatest economic alliance trading partnership in the history of humankind and it is only going to grow," US Secretary of State John Kerry told a meeting of bosses from top Chinese and American companies.

From small beginnings of about $2.5 billion in 1979 when formal diplomatic relations were established, annual trade between the two economic giants has now grown to a gargantuan $520 billion.

Direct foreign investment between the two has also ballooned, and last year for the first time the amount of investment flowing from China surpassed that from the United States.

"We want to do better," the top US diplomat said.

But there have been a series of US-China trade disputes, while the United States has long insisted that the Chinese yuan, or renminbi, is artificially undervalued.

While the US has not branded China a currency manipulator, which could entail sanctions, it has complained that the weak yuan gives China an unfair trade advantage.

Kerry also highlighted strains over protecting intellectual property as well as concerns over sharing information technology.

"We need to make sure we're protecting intellectual property rights, make sure we're creating transparency in the regulatory process, make sure we are raising the bar for everybody in terms of the standards by which we do business," Kerry said.

The CEOs of such companies as General Electric, Boeing, Fedex, Goldman Sachs and Silicon Valley Bank gathered for the working breakfast with counterparts from large Chinese firms including China State Construction Engineering Corporation, the Wanxiang Group, Dalian Wanda Group and the Shuanghui Group.

- Breaking the logjam -

"Business is a backbone of the China-US economic relationship," said State Councillor Yang Jiechi, speaking at the meeting on the sidelines of a two-day annual Strategic and Economic Dialogue summit.

"Trade and investment between our business leaders, big businesses, not only brings goods and jobs to us but also mutual understanding and friendship among our peoples."

The top US trade envoy said earlier this week that the US wants China to break a logjam over a proposed World Trade Organization information technology pact.

China should show "real leadership" by helping to advance negotiations on expanding the WTO's Information Technology Agreement (ITA), US Trade Representative Michael Froman said.

Froman, who attended Thursday's breakfast pow-wow, would not comment on a Financial Times report that the standoff was over China's drive to exclude about 60 new product categories, including medical devices and next-generation silicon chips from the ITA.

But he suggested that if China showed more willingness to negotiate the ITA deal, it could help smooth the way to reach common ground on other troublesome issues.

US administration officials and lawmakers have repeatedly lambasted Beijing for failing to play by global rules, and the breakfast event was billed as a way for major companies from both nations to air difficulties and grievances they have encountered.

"It is important that these firms are able to participate in healthy competition -- on a level playing field -- that will produce benefits for both of our nations and the global economy," US Treasury Secretary Jacob Lew said.

Earlier this month the World Trade Organization called on China to make its trade policies more transparent amid a "striking" lack of clarity on its rules.

China, which recently become the largest trader in the 160-member group, has failed to live up to key transparency commitments it made when it joined the organisation in 2001, WTO members said.