WASHINGTON - The White House on Tuesday expressed concern about the arrests of political dissidents in Vietnam, saying the detentions were out of character for Vietnam's recent modernization.

President George W. Bush later in the day planned to meet four prominent Vietnamese-American democracy advocates to discuss ways to promote greater freedom and openness in Vietnam.

Bush had hailed Vietnam's vibrant economy on a goodwill visit to Hanoi last November, but an air of disenchantment has set in at the White House.

A Vietnam court on May 11 sentenced two activist lawyers to up five years in jail in the latest trial of political dissidents in the communist-run state.

"The United States has been concerned by the increasing incidence of arrest and detention of political activists in Vietnam for activities well within their right to peaceful expression of political thought," said Gordon Johndroe, spokesman for the White House National Security Council.

He said as economy and society reform and move forward, "such repression of individuals for their views is anachronistic and out of keeping with Vietnam's desire to prosper, modernize and take a more prominent role in world affairs."

Hanoi rejects accusations by Western human rights groups that it has cracked down on activists after Vietnam successfully hosted an Asia-Pacific summit, won World Trade Organization membership and was removed from a U.S. religious rights blacklist in 2006.