More than two decades after doi moi - the "renovation" that opened Vietnam to the outside world - some conservative elements in the Communist party are rattling foreign investors by trying to put the brakes on reform.

In a series of recent announcements, government officials have introduced plans for price controls and import restrictions that have drawn foreign investors, who are normally discreet in their criticism of the government, into the open.

"Vietnam's leadership is currently seeking an irrational step back in time to resolve the issue of curbing potential inflation, thereby putting in jeopardy much of what has been achieved in Vietnam in recent years," Matthias Dühn, head of the European Chamber of Commerce in Vietnam, wrote recently on the chamber's website. The measures outlined in circulars issued by the government are designed to correct emerging economic imbalances but foreign businessmen say they are crude and would be ineffective.

"We are sensitive to the dangers of rising inflation and other economic challenges that Vietnam is facing. However, we do not believe the proposed circular will help achieve the government's economic goals," Hank Tomlinson, the president of Chevron Vietnam and chairman of the American Chamber of Commerce, wrote in an open letter to the finance minister.

One foreign economist who studies Vietnam says of the proposed measures that "in terms of a public relations strategy, it is not good news".