Singapore has stuck to its 18-year ban on the import and sale of chewing gum, which has become an international symbol of the city-state's image as a strict society.

'The government stands by its decision to ban chewing gum,' Maliki Osman, parliamentary secretary at the Ministry of National Development, told parliament.

He added: 'Chewing gum has not been a significant problem since that ban took effect.

'There have been concerns that lifting the ban on chewing gum could result in chewing gum litter and undermine ongoing efforts to curb littering.'

Mr Osman said as the reason for the imposition of the ban is still valid, 'the government's position is that the ban shall remain'.

He was responding to a question in parliament from Denise Phua, a fellow member of the ruling People's Action Party, who argued that the ban had been used by Singapore's detractors to criticise its tough governance laws.

'I think this ban ... now needs a re-thinking. Surely (Singapore) will not consider banning sweets because of sweet wrapper litter or ice-cream stick litter,' she said.

Singapore banned the import and sale of chewing gum in 1992 in an attempt to eradicate the problem of people sticking the gum on chairs, tables, lifts and other public areas.

One of the key reasons for the ban had been the disruption of services on Singapore's subway train system because of chewing gum being stuck on the doors and causing delays.

Singapore partially lifted the ban in 2004 by allowing the sale of chewing gum used for health reasons, such as dental health gum, after the conclusion of a US-Singapore Free Trade Agreement.