(AFP) Opposition party Keadilan today joined the criticism of Singapore for banning schoolgirls from wearing Islamic headscarves.

Party president, Wan Azizah Wan Ismail, who wears a headscarf herself, urged the Singapore authorities to exercise religious understanding and tolerance.

"Just as the attire of Sikhs, nuns and monks do not contribute to social disharmony, we believe the choice of wearing a certain attire by Muslims would not lead to social disintegration," she said in a statement.

"In fact, tolerating and facilitating the expression of religion as understood by adherents of a particular faith could only lead to a society imbued with tolerance and moral virtues."

Four Muslim schoolgirls in Singapore were threatened with suspension for wearing headscarves scarves at school. The scarves, or tudung, can be worn to and from school but have to be taken off during lessons under strict Singaporean rules designed to promote racial harmony.

Two students have now complied with the rules after pressure from the authorities, and two others were given until Monday to fall in line or face expulsion.

Other politicians have also criticised Singapore's stance but the city-state has objected to interference in its internal affairs.

Malaysia has a majority Muslim population with a large Chinese minority, while Singapore is dominated by ethnic Chinese with a Muslim minority.