LAST seen in swimming trunks, Chinese Prime Minister Li Peng is expected to be wearing more formal attire when he meets his Thai counterpart, Chuan Leekpai, in Beijing this morning. Apart from last week's seaside photograph, today's meeting will be Mr Li's first public appearance since he met Australian Prime Minister Paul Keating on June 24. A Foreign Ministry spokesman said Mr Li would preside over a welcome ceremony at the Great Hall of the People, then hold talks with the Thai head of government at the state guest house. Mr Li is still officially described as ''ailing'' and it is not clear if today's meeting with Mr Chuan represents a formal resumption of his duties or simply a public gesture to dampen speculation about his health, both physical and political. The Prime Minister has spent the past four months recuperating from a mild heart attack during which time he has made only two public appearances. Many political analysts believe that, health permitting, Mr Li will attempt to reassert his influence on economic matters. Mr Li will be anxious to re-establish his political standing before the key plenary session of the Communist Party's Central Committee which is expected to convene in early October, according to analysts. It is unclear, however, if Mr Li can wrest enough of the economic portfolio away from his deputy, Zhu Rongji, to make a significant impact on the political decision-making process before that date. Mr Zhu has monopolised economic policy making since Mr Li's heart attack and is rumoured to be on the verge of announcing a major new economic reform package. However, analysts pointed out that Mr Li still had the support of several influential party elders and it would not be easy to sideline him entirely. Mr Li's experience in economic policy making would also be to his advantage. ''Li Peng's warnings about economic overheating have clearly turned out to be right, so in that sense they will still have to listen to what he has to say,'' a Western diplomat said. ''I think it is clear that Deng [Xiaoping] wants to get rid of him but Li Peng is not going to go quietly or without a fight,'' he added.