BANGKOK, June 1 (Reuter) - A U.S. Congressman said on Thursday there was a danger of conflict with an expansionist China and that the United States and Southeast Asian countries must work together to deter Chinese aggression.

"We can expect to face a hostile, expanding and anti-democratic China in the future and I am extremely concerned about that," Congressman Dana Rohrabacher told a news conference.

"A conflict situation with communist China could destroy all of the progress that is being made today in Southeast Asia," he said.

Rohrabacher, a Californian Republican, is on a private Asian tour which included a visit to Laos where he inspected refugee repatriation centres.

He criticised China's human rights record, its policy in Tibet, its support for Burma's military government and what he described as its bullying over the disputed Spratly Islands of the South China Sea.

He said stronger political and military ties between the United States and the Association of Southeast Asian Nations (ASEAN) members would be beneficial to all parties.

ASEAN groups Brunei, Indonesia, Malaysia, the Philippines, Singapore and Thailand.

"The way you deter confict with a non-democratic country is to be firm and strong and principled. The Chinese regime has to know that we will not permit them to bully their neighbours and we do not accept their gross violations of human rights," Rohrabacher said.

"Together, the United States and the ASEAN countries, we must work together to avert a possible conflict with China by being strong and standing together," he said.

"Unless we deal with it now and let the Chinese regime know that what they're doing is unacceptable, we will all pay the price."