THE United States is under growing pressure to drop its objections to the resumption of ADB loans to Vietnam, one of the bank's oldest members. A United States delegation spokesman responded to the clamour yesterday by saying that for the moment there was no change in policy but that the US would review its stand before the IMF meeting in June. The ADB has been prevented from extending new loans to Hanoi for nearly 20 years because of US opposition. The US and Japan are the biggest contributors to the ADB. Vietnam ADB governor Cao Sy Kiem said: ''Vietnam is proud of being one of the founding members of the Bank and of joining efforts with other member countries in the construction and development of the bank for more than a quarter of century now. ''We think we should be treated as other member countries. ''This is in conformity not only with the spirit and letters of the bank's charter but also with the rationale and present reality.'' Mr Cao told the board of governors that Vietnam's economy had continued to stabilise last year with a growth rate of 8.3 per cent, improved balance of payments and reduced inflation of 17.5 per cent, compared with 67.2 per cent in 1991. He added: ''After several years of trying to overcome many difficulties at home and unfavourable factors from outside, we have basically transformed our command economy into a market-oriented economy.'' However, the ADB 1992 annual report shows Vietnam faces major impediments, including poor infrastructure, backward financial system and stifling regulatory climate - all hold-ups that could be readily relieved with the regional development bank's financial and technical help. Washington has vowed to maintain and trade and economic embargo on Hanoi, which launched successful market reforms in 1986, until it fully accounts for more than 2,200 US servicemen listed as missing or imprisoned during the Vietnam War. ADB governor for Canada, Benno Friesen, said: ''We look forward to the normalisation of Vietnam's relations with the international financial institutions. ''We believe that lending can resume once it clears its arrears, reaches an agreement with the IMF, and meets appropriate performance criteria including issues of good governance.'' The ADB has been preparing to resume lending for development projects in Vietnam once United States objections are lifted. The last ADB loan to Vietnam was approved in 1974 for the Industrial Development Bank, five months before the communist north captured the US-backed south, triggering the US trade embargo. Vietnam's invasion of Cambodia in 1978 made matters worse, prompting the suspension of multilateral and bilateral programmes. Vietnam pulled out of Cambodia in 1989. The ADB won approval last November to release special funds to grant a special US$67.7 million rehabilitation loan to help rebuild Cambodia if this month's general election succeeds. Vietnam is a member of the World Bank, IMF and the ADB, but the three have withheld loans to Hanoi since Washington extended its 1964 trade embargo on North Vietnam to cover the entire country in 1975.