Singapore has barred a prominent Malaysian lawyer, who is fighting a ban on Muslim schoolgirls wearing headscarves, from working in the city-state.

Malaysian constitutional lawyer and opposition politician Karpal Singh was working on behalf of four families who had defied Singapore's ban on the scarf or tudung.

Mr Karpal Singh's application was rejected because there are grounds to conclude that his motive is to intervene in Singapore's internal affairs

Ministry of Manpower statement

Three of the girls - aged six to seven-years-old - were barred from school in February for continuing to wear the headscarves.

Another girl was suspended from classes in 1997.

The authorities insist they instituted the secular dress code to promote ethnic harmony.

Singapore has been careful to avoid racial and religious tensions between its ethnic Chinese majority and the Malay Muslim minority since race riots in the 1950s and 60s.

But Muslims say the headscarf ban infringes their religious freedoms.

Double standard

The ban provoked a rare show of open defiance against Singapore's strict government.

Mr Singh has argued the measure is "unlawful, discriminatory and unconstitutional" - especially in light of the fact that schools in the city-state allow Sikh boys to wear turbans.

The prime minister warned against seeking foreign help

Mr Singh had applied to work in the Singaporean law firm which has been handling the girls' case as a "lawyer and consultant on constitutional matters", the Ministry of Manpower said in a statement on Friday.

"Mr Karpal Singh's application was rejected because there are grounds to conclude that his motive is to intervene in Singapore's internal affairs," the ministry said.

It accused Mr Singh of wanting to "further his own agenda" by taking the headscarf issue to court.

Mr Singh described the accusation as "unwarranted and without any basis" and said he would demand an explanation from the Singaporean Government.

Muslims under pressure

Mr Singh is a well-known lawyer who represented former Malaysian deputy leader Anwar Ibrahim when he was tried for corruption and sodomy, He has represented clients in Singapore before.

The ban on the Muslim headgear comes at a sensitive time following last September's attacks in the US, which was blamed on Islamic extremists.

In February, soon after the row erupted, Prime Minister Goh Chok Tong warned Muslims against seeking support abroad, saying it would make some people even more suspicious of Muslims.

"For them now to try to push the wearing of the tudung in schools will only cause greater concern to the non-Muslims, so I would advise them to be quite cautious in this," he said.