Dianne Feinstein, a long-serving Democratic US senator from California and gun control advocate who spearheaded the first federal assault weapons ban and documented the CIA's torture of foreign terrorism suspects, has died at 90, US media reported on Friday.

Feinstein's office did not immediately respond to a request for comment on the news, first reported by the Punchbowl news outlet.

Feinstein was a Washington trail-blazer who among other accomplishments became the first woman to head the influential Senate Intelligence Committee.

During almost 31 years in the Senate, she amassed a moderate-to-liberal record, sometimes drawing scorn from the Left. Feinstein joined the Senate in 1992 after winning a special election and was re-elected five times including in 2018, along the way becoming the longest-serving woman senator ever.

Feinstein's political career was shaped by guns.