London's Metropolitan Police said Monday they were investigating an allegation of sexual assault in 2003, after a joint investigation into the comedian and actor Russell Brand by three British media outlets was published Saturday.

The Sunday Times, The Times and Channel 4's "Dispatches" published an investigation in which four women alleged Brand sexually assaulted them in separate instances between 2006 and 2013. One of the women said she was 16 and Brand was 31 at the time of the alleged assault in London.

Without naming the British comedian -- who denies the allegations -- a Met spokesperson said on Monday: "We are aware of reporting by The Sunday Times and Channel 4's Dispatches about allegations of sexual offenses.

"On Sunday, 17 September, the Met received a report of a sexual assault which was alleged to have taken place in Soho in central London in 2003. Officers are in contact with the woman and will be providing her with support."

Downing Street also commented on the claims in the documentary.

"These are very serious and concerning allegations," Prime Minister Rishi Sunak's official spokesman said Monday. "The Met Police has asked anyone who believes they have been a victim of a sexual assault to come forward to speak to officers."

Brand preemptively denied the allegations in a video posted to his verified Instagram page, which he shared on Friday before the report was published. In the video, Brand described the claims as "very serious allegations that I absolutely refute."

The women chose not to be identified by name in the report, according to The Times. CNN has not been able to independently verify their claims.

Brand's upcoming show at the Theatre Royal Windsor for his "Bipolarisation" tour has been postponed, following the publication of the joint investigation.

The theater shared a statement from the promoters of the tour, saying: "We are postponing these few remaining addiction charity fundraiser shows, we don't like doing it - but we know you'll understand."

Media companies launch investigations

The claims against Brand -- who was a prominent figure on multiple UK television channels during the period in which the alleged assaults occurred -- have spurred media companies that formerly employed Brand to launch internal investigations.

A BBC spokesperson said Sunday: "The documentary and associated reports contained serious allegations, spanning a number of years. Russell Brand worked on BBC radio programmes between 2006 and 2008 and we are urgently looking into the issues raised."

The BBC had "evolved its approach" toward talent and complaints over successive years, the spokesperson added, and had "clear expectations around conduct at work." The broadcaster would "always listen to people if they come forward with any concerns, on any issue related to any individual working at the BBC, past or present."

Channel 4 has also removed all programs linked to Brand from its online platform.

"We've taken down all content featuring Russell Brand while we look into the matter. This includes episodes of the Great British Bake Off and the Big Brother box sets that he appeared on," a Channel 4 spokesperson told The Telegraph on Sunday evening.

Russell Brand's career

Brand has denied claims he said were put to him "in a letter and an email" from a "mainstream media TV company" and "newspaper." Brand did not name the organizations, but said the communications listed "a litany of extremely egregious and aggressive attacks."

"Amidst this litany of astonishing, rather baroque attacks, are some very serious allegations that I absolutely refute," Brand said his a video shared on social media.

Brand shared the video with his 11.2 million followers on X, formerly Twitter, and his 3.8 million followers on Instagram.

Brand gained fame as a comedian and actor, appearing initially in UK reality TV shows and films, and later a number of Hollywood movies.

In recent years he has built a vast digital platform around wellness.