Burma has named a senior army officer as a temporary replacement for Prime Minister General Soe Win, who is thought to be suffering from cancer.
Thein Sein (centre) ranks among the highest army officers
Lt Gen Thein Sein, who ranks fifth in Burma's military, was referred to as acting prime minister in the state-run New Light of Myanmar newspaper.
It is thought he will greet Cambodian leader Hun Sen, who arrives on an official visit next week.
Soe Win has recently visited Singapore for medical treatment.
Officials have not confirmed his illness, but he is believed to be suffering from leukaemia.
'Serious health matter'
Thein Sein has conducted a number of official duties during Soe Win's illness - carrying out high-level negotiations with Bangladesh and Cambodia.
Burmese state media has variously referred to him as first secretary of the Myanmar State Peace and Development Council, and chairman of the National Convention Convening Commission.
Soe Win, an army general aged in his late 50s, travelled to Singapore in late February on what the city-state's foreign ministry called a "private visit".
But Burma's embassy in Singapore later said he was being treated for a "serious health matter".
He has been prime minister since 2004, when he replaced ousted Khin Nyunt.