Officials also said they will consider raising the conservancy charges for the dirtiest precincts to cover the extra work that goes into maintaining them.

The index, the first of its kind in Singapore, was unveiled on Saturday by the GRC's Members of Parliament.

They said that it was designed to encourage residents to change their attitudes towards tossing trash.

Aljunied Town Council chairman Cynthia Phua said that the index would be based on the cleanliness of lifts, the condition of public property and how large pieces of rubbish are disposed.

She told The Straits Times yesterday that the council would tie conservancy charges to the index only if it found an objective measure of cleanliness.

The plan is under consideration and would not be confirmed until next year, she said.

To keep the area clean, the town council is also installing cameras in lifts and void decks in 500 flats, in a five-year project estimated to cost $7.5 million.

This will help with the problem of people urinating in lifts, which has continued despite the installation of urine detectors.

Madam Phua said that in 20 blocks of flats where cameras had been set up, lifts have become cleaner.

Some HDB dwellers who spoke to The Straits Times said that they supported tying cleanliness to conservancy charges, but wanted to know how things would be measured.

Project manager Chong Kwang Heng, 34, who rarely sees trash in his area, said that the plan would make people think twice before littering.

He added: 'If they can find a fair way of measuring cleanliness, then it's fine. The plan sounds reasonable.'

Other town councils are not yet considering the same move.

Dr Teo Ho Pin, coordinating chairman of the 14 People's Action Party town councils, had reservations about the plan.

He said it means a few litterbugs at a block could end up causing everyone to be punished.

The North West District mayor pointed to a case where someone who was mentally ill kept dousing a lift with urine, irking other residents.

The problem was solved after his family was notified and stepped in.

'We should be telling people: 'This is your home, take care of it.' If we take punitive measures, it may cause a lot of friction among people,' said Dr Teo.

He added that although conservancy charges have been rising - by about 15 per cent - they involve more than just cleaning costs. The charges are also for maintaining the electric wires, landscaping and lifts, he noted.

siewtha@sph.com.sg