The terms of the controversial Proposition 227 will replace the state's existing bilingual education system.

Under the new system classes will be taught exclusively in English from the second school year onwards.

Parents can request bilingual education for their children, but only under limited conditions.

About 60 per cent of Californians approved the change in the system.

Hispanic activists said they were considering a legal challenge to the vote.

A spokesman for the Mexican American Legal Defense and Educational Fund, Thomas Saenz, said campaigners would take the necessary steps to prevent the abolition of bilingual teaching being implemented.

'Ethnic ghetto' fears

For the past 30 years, Californian schools have taught non-English speakers in their mother tongue - mainly Spanish - and let them learn English gradually.

But that system has been criticised because it has left thousands of youngsters unable to function properly in English.

Proposition 227 is the initiative of millionaire Republican businessman, Ron Unz, who says the failure of California's bilingual education programme has resulted in the segregation of students by language.

Nearly 1.5 million pupils - a quarter of the state schools' population - have a poor knowledge of English, speaking Spanish as a first language instead.

Critics of the current system say that it has resulted in Hispanics being condemned to 'ethnic ghettos'.

It is estimated by the year 2040, Hispanics will make up almost two-thirds of the population of California.

Children could fall behind

The measure has also been fiercely opposed by the California School Boards Association and the state's parent-teacher association, which complains that it takes away parents' right to choose what is best for their children.

There are also worries that Hispanic children will fall behind in school because they will be unable to follow what is being said.

The Clinton Administration is also against the measure, and expressed disappointment with the outcome of the vote.