WASHINGTON, June 22 - U.S. Trade Representative Ron Kirk is expected to launch a WTO case against China on Tuesday when he holds what his office called a major news conference regarding U.S.-China trade.

Kirk's office gave no details in announcing the 9:15 a.m. EDT/1315 GMT session with reporters. But industry sources said they expected the United States and the European Union would both announce a World Trade Organization case against China over its export restrictions on raw materials.

The expected action by the United States and the EU follows their failure to persuade China to reduce its export tariffs and raise quotas on materials such as zinc, tin, tungsten and yellow phosphorous.

The first step, which industry sources expect to be announced on Tuesday, would be for Brussels and Washington to formally request consultations with Beijing. If these talks fail, the next step would be to request that a WTO panel hear the complaint, a step that can take years.

"If the US and the EU do indeed file a WTO case against China on raw material export restrictions, we welcome this action," said Tom Gibson, president of the American Iron and Steel Institute.

"US and NAFTA steel producers have long believed that this government of China policy is a WTO violation and that it is benefiting Chinese manufacturers artificially while disadvantaging manufacturers everywhere else," he said.