California's legislature has become the first in the US to approve a bill banning caste discrimination.

Legislators said the measure would protect people of South Asian descent who allege unfair treatment.

The governor must now decide whether to sign the bill into law. Seattle became the first US city to ban caste discrimination in February.

The measure, which passed on Tuesday by 31-5, was sponsored by Democratic state senator Aisha Wahab, who said it would add caste as a protected category in the state's anti-discrimination laws alongside gender, race, religion and disability.

Five Republican state senators voted against the legislation, arguing that discrimination was already illegal under state law.