A survey of California residents has found the highest levels of support yet for allowing same-sex marriage.

For the first time, more respondents were in favour of gay marriage than against it.

The survey of 2,002 people found 50 per cent for gay marriage and 45 per cent against it.

The Public Policy Institute of California, which carried out the research, said support levels had never risen above 45 per cent since the question was first asked in 2000.

Democrats and independents were most likely to support the move, with 64 pr cent and 55 per cent in favour respectively. Sixty-seven per cent of Republicans were against gay marriage.

California has been the most high-profile battleground for same-sex marriage in the US in the last few years.

Gay couples were given the right to marry in 2008 but opponents succeeded in having this struck down at the polls just several months later.

The Supreme Court turned down an appeal by gay rights groups last year, although a trial examining whether the ban was constitutional is currently on hiatus and expected to resume shortly.

All of the 18,000 couples who married in the brief window have been permitted to remain married.

The survey also asked Californians whether they agreed with gays and lesbians serving openly in the military. Seventy-five per cent agreed that they should be allowed to.