WASHINGTON (AFP) - The United States and China on Monday aired out concerns about hacking, which has emerged as a major irritant between the world's two largest economies.

US and Chinese officials met in Washington for the first session of a "cyber working group", two days before the countries hold their main annual talks.

A State Department official said the inaugural session would let the two sides "raise concerns, develop processes for future cooperation and set the tone" on cyber issues.

"We will continue to raise issues of strategic concern, including the cyber-enabled theft of intellectual property, trade secrets and confidential business information for economic gain," he said.

The US has accused China of waging a vast hacking campaign against the US government, military and companies, with a private study recently concluding that cyber-theft costs the US economy hundreds of billions of dollars a year.

China has hit back that it is also the victim of cyber attacks, charges that gained ammunition when the intelligence leaker Edward Snowden said US spies had hacked into the prestigious Tsinghua University, one of six centers that routes all of China's Internet traffic.

President Barack Obama has insisted that there is a distinction between intelligence gathering, which he said all countries conduct, and the theft of trade secrets for commercial gain.

Hoping to ease the rift, Secretary of State John Kerry and State Councilor Yang Jiechi, a key figure in setting China's foreign policy, in April announced the start of the cyber dialogue.

Mr Yang and Vice Premier Wang Yang will visit Washington for the annual Strategic and Economic Dialogue with Kerry and US Treasury Secretary Jacob Lew on Wednesday and Thursday.

The cyber talks involved Christopher Painter, the State Department's coordinator for cyber issues, and Defence Department official Eric Rosenbach.