Mr Choi Shing Kwok, Permanent Secretary at the Ministry of the Environment and Water Resources, will retire on Oct 1, after 36 years of service in the public sector.

Mr Choi, 58, will be replaced by Mr Albert Chua, who will relinquish his appointment as the Second Permanent Secretary for Foreign Affairs, the Public Service Division (PSD) said in a statement yesterday.

As Permanent Secretary for the Environment and Water Resources since 2012, Mr Choi "made significant contributions in providing Singaporeans with a quality living environment", the PSD added.

His contributions include developing a comprehensive approach to deal with haze pollution and playing a key role in the development of the landmark Transboundary Haze Pollution Act.

Mr Chua, 49, served in various posts in the Ministry of Foreign Affairs before he was appointed principal private secretary to then Prime Minister Goh Chok Tong in 2004. He was appointed Singapore's high commissioner to Australia in 2008 and, in 2011, permanent representative to the United Nations in New York. Mr Chua has been Second Permanent Secretary for Foreign Affairs since 2014.