The United States is pushing hard for the release of Chinese political prisoners ahead of a visit to Beijing in June by President Clinton, a top administration official said Friday.

But Undersecretary of State Thomas Pickering, in Beijing to lay the groundwork for the first visit to China of a U.S. president in nine years, had no word on possible freedom for imprisoned student activist Wang Dan.He indicated that human rights, along with trade and weapons control issues, would top the agenda during Clinton's summit with Chinese President Jiang Zemin.

Also on the table would be cooperation in energy and the environment and advancing military ties.

"The release of dissidents is a very important part of the policy objective," Pickering told a news conference.

U.S. administration officials have said privately they are hopeful that Wang, a leader of the 1989 Tiananmen Square democracy movement now serving an 11-year jail term, would be set free before the summit, or possibly after.

But Pickering said, "I'm not in any position to give you any prediction of the release of any particular individual.

"We made our case very strongly about such releases," he added.

Pickering said he told Chinese officials, including Vice Premier and former Foreign Minister Qian Qichen, it was "extremely important" for China to sign the U.N. International Covenant on Civil and Political Rights very soon.

The pact guarantees a wide range of freedoms that Beijing now limits, including the rights to free speech, assembly and worship.

China's promise to sign the agreement was rewarded by a decision by the United States and European Union nations not to sponsor a resolution critical of Beijing at a meeting of the U.N. Commission on Human Rights now under way in Geneva.

Pickering said the summit offered an ideal target to bring Beijing into the World Trade Organization, but negotiations had a long way to go.

He said Washington would like "the earliest possible agreement."

"The summit, in that regard, will be an ideal target," Pickering said.

But he added: "They and we both expressed realistic views that there is a long way to go to achieve WTO accession."

China has been battling for 11 years to join the trade body, but the United States and other trading partners insist it must offer deeper tariff cuts and open wider its market for services, including banking and insurance.

Pickering's trip is one in a series of pre-summit missions to Beijing by top administration officials.

Acting Undersecretary of State John Holum, who handles arms control and international security, recently visited.

U.S. Trade Representative Charlene Barshefsky arrives later this month for a tough bargaining session on trade.

And Secretary of State Madeleine Albright will be in the Chinese capital on April 29 and 30.