VALUABLE mangrove swamps and coral reefs that were not earmarked as nature areas in the latest draft of the Government's new land-use master plan, had to be left out to give Singapore options to develop these areas for other critical needs.

Explaining the Urban Redevelopment Authority's (URA) decision, which has made greenies here see red, National Development Minister Mah Bow Tan yesterday said that land-scarce Singapore cannot afford to protect all its nature areas.

Using Sungei Khatib Bongsu as an example, he said the mangrove swamps there might have to go if the area is needed for a reservoir.

The Straits Times reported last week that Sungei Khatib Bongsu, which is near the Lower Seletar Reservoir, will be dammed up to form a reservoir as part of plans to meet Singapore's long-term water needs.

Environmentalists are riled that this area, along with mangroves near Sungei Mandai, was left out of the URA's draft of the Master Plan although it was listed in the 1993 Singapore Green Plan.

Also left out were marine sites off the shores of St John's Island, Pulau Hantu, Pulau Semakau and Pulau Sudong - all of which are popular with divers because of the underwater coral reefs.

Replying to media queries during a walkabout in Tampines yesterday, Mr Mah said: 'We've had to hold back the gazetting of some areas because once you do that, you have to be absolutely sure that we can keep it green in the long term.

'Unfortunately, we're not sure if we need these areas in the long term. So we take the conservative approach - let's not put them in the Master Plan for this period, which is for about five years.

'Let's review it every five years, rather than close off our options.'

He promised that the Government would try to avoid encroaching onto green areas 'as much as we can' and to keep them green 'as long as possible'.

He admitted he had no idea how long that would be but it would definitely be more than five years and might even stretch to 20 years.

'Realistically, that's how we have to work in Singapore,' he said. 'Within this 600 sq km, we've got to provide enough for everything, including our survival.'

Nature lovers accepted this reasoning but remained upset that the areas were quietly dropped from the Master Plan.

Said Nature Society's conservation committee chairman Ho Hua Chew: 'The Master Plan shows that there's no definite plan for the areas at the moment. That means they remain as green areas. If so, they should be marked as such and not be downgraded...

'If they are not marked as nature areas, they become like any other land in Singapore - they can be developed and no one can ask any questions.'