U.S. Trade Representative Ron Kirk expressed hope a dispute over China's support for domestic wind turbine manufacturers can be resolved before a World Trade Organization panel hears the case.

"We're actively engaged in very productive discussions with China," Kirk said in a speech at the National Bureau of Asian Research. Asked later if he thought the two sides could resolve the dispute before it moves to the formal litigation stage, Kirk said: "I hope so.

The United States has filed the case because of concerns that Chinese wind turbine manufacturers receive government subsidies that give them an unfair advantage over U.S. and other foreign producers.

Under WTO rules, countries are required to initially try to resolve disputes through consultation. If those efforts fail, the concerned party can request the WTO establish a dispute settlement panel to decide the issue.

In wide-ranging remarks, Kirk also seemed to resist the suggestion of a senior congressional Democrat that the White House try to force a vote on a free trade pact with South Korea.

Republicans, who generally support the agreement, have threatened to block it unless President Barack Obama sends two other long-delayed trade pacts -- with Panama and Colombia -- to Congress for a vote.

Kirk said the White House wanted to win approval of all three agreements, and that he was confident that talks with Colombia and Panama to resolve remaining concerns would be successful. When to send Congress the agreements was a matter for the White House to decide, he said.

On another issue, Kirk said the United States remains very much interested in Japan joining negotiations on a proposed regional free trade agreement known as the TransPacific Partnership pact.

But Washington understands that Japan's first priority is guiding the recovery from its catastrophic earthquake and tsunami and the crisis at the crippled Fukushima nuclear power plant, he said.

Japan has been expected to decide by June whether to ask to join the TransPacific Partnership talks with the United States, Chile, Singapore, Australia, Malaysia, Vietnam, New Zealand, Brunei and Peru. (Reuters)