The families of four Muslim schoolgirls who were suspended from their schools in Singapore for wearing Islamic headscarves are planning to sue the government.

Three of the girls - aged six to seven years old - were barred from school in February after a highly-publicised stand-off between the families and the city-state, which said the scarves flouted school rules.

What we are saying is that this is unlawful, discriminatory and unconstitutional Karpal Singh, lawyer

"The directive given by the Ministry (of Education) to the school principals not to allow these three daughters, school children to put on their headscarves - it's unconstitutional," their lawyer, Sadari Musari, told Reuters on Monday.

The family of a fourth girl, barred from class in 1997, is also bringing a case against the state.

'Unconstitutional'

Karpal Singh, a prominent constitutional lawyer engaged as counsel for the four families, said: "What we are saying is that this is unlawful, discriminatory and unconstitutional".

Singapore says the headscarf ban is intended to promote racial and religious harmony,

Many Malay Muslims wear a scarf from a young age

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

But Mr Singh said the case should be viewed as a purely legal matter.

"This should not be mistaken because this is actually a legal issue. A lot of people might inject into this a political dimension but that should not be the case," he said.

For devout Malay Muslims, the headscarf, or tudung, is obligatory once girls reach puberty but some parents choose for their daughters to wear them earlier.

The Islamic Religious Council of Singapore (Muis) has said that education is more important than wearing the headscarf.

Mr Sadari said he expects the lawsuits to be filed with Singapore's High Court within the next two weeks but declined to comment on damages the families were seeking.