SINGAPORE, March 21 (Reuters) - Myanmar Prime Minister Soe Win is being treated at one of Singapore's top public hospitals but is not critically ill, an official at the Myanmar embassy said on Wednesday. Soe Win, who is in his late fifties, is being treated at Singapore General Hospital where his ward is guarded by Singapore police, the official said. Military-ruled Myanmar's junta leader Than Shwe, who is 74, also received treatment at the same hospital in January. The official declined to give details of Soe Win's medical condition but said that a team of doctors was looking after him, including a couple of specialists who had flown in from Yangon. "He is ill, but not critically ill, not at the moment," said the official, who declined to be named. The Irrawaddy, a Thailand-based journal that covers Myanmar, reported last week that Soe Win may be suffering from leukaemia. Soe Win, an army general, replaced former prime minister Khin Nyunt who was purged in October 2004. The United States has accused Soe Win, a trusted Than Shwe deputy, of direct involvement in the May 2003 attack by pro-government youths on Myanmar's democracy icon, Aung San Suu Kyi, and her supporters. The attack, near Mandalay, led to her detention. The embassy official said Soe Win arrived in Singapore more than two weeks ago, but could not say when the Prime Minister would return to Myanmar, formerly Burma.