A California senator who has staunchly opposed homosexual rights now says he is gay, ending days of speculation that began after his arrest last week for investigation of driving under the influence.

Roy Ashburn, a conservative Republican, came out in an interview with KERN radio on Monday.

Ashburn said he felt compelled to address rumours that he had visited a gay nightclub near the Capitol before his drunken driving arrest.

"I am gay ... those are the words that have been so difficult for me for so long," Ashburn told conservative talk show host Inga Barks.

The 55-year-old father of four said he had tried to keep his personal life separate from his professional life until his March 3 arrest.