The Monetary Authority of Singapore (MAS) has moved quickly to dispel rumours that its executive chairman, Richard Hu, and its deputy managing director, Koh Beng Seng, have resigned. Mr Koh submitted his resignation last month, but was persuaded to stay by Prime Minister Goh Chok Tong. There are now new rumours that he has tried to quit again, along with his mentor Mr Hu, who is also the highly respected Finance Minister. No official reason was given for Mr Koh's initial move last month. Talk in the banking community is that it could be related to a government review of Singapore's financial sector chaired by Deputy Prime Minister Lee Hsien Loong. Sources believe the review will probably lay the blame for Singapore's lack of vibrancy - when compared with Hong Kong - on the authority's tendency to over-regulate and Mr Koh's autocratic style. Foreign bankers have complained that Mr Koh treats them like 'crooks'. Mr Hu is well-known as a fan and guardian of Mr Koh. When Mr Koh tried to quit last month, Mr Hu was quick to come to his defence.