- The actor and comedian said he had received letters from a TV company and newspaper, containing "a litany" of "aggressive attacks".
- He started his career as a stand-up comedian in the early 2000s but got his big break a few years later as the host of Big Brother's Big Mouth on E4.
Russell Brand has released a video in which he denies "serious criminal allegations" that he says will be made against him.
The actor and comedian said he had received letters from a TV company and newspaper, containing "a litany" of "aggressive attacks".
The BBC understands that a number of women will make serious allegations about Brand's sexual conduct in a Channel 4 Dispatches programme and Sunday Times report expected to be aired and published this evening.
His relationships were "always consensual", Brand said.
In the video, posted on YouTube and X, formally known as Twitter, Brand said: "Amidst this litany of astonishing, rather baroque attacks are some very serious allegations that I absolutely refute.
"These allegations pertain to the time when I was working in the mainstream, when I was in the newspapers all the time when I was in the movies, and as I've written about extensively in my books I was very, very promiscuous.
"Now during that time of promiscuity, the relationships I had were absolutely, always consensual."
Brand said he believed he was the subject of a "co-ordinated attack" and he was going to look into the matter because it was "very, very serious".
He did not name the TV company or newspaper in his video.
Brand has hosted a number of radio and TV programmes for networks including Channel 4, MTV, Radio X, and the BBC.
He started his career as a stand-up comedian in the early 2000s but got his big break a few years later as the host of Big Brother's Big Mouth on E4.
After his profile surged, Brand was cast in Hollywood films such as Forgetting Sarah Marshall, Get Him To The Greek and Arthur.