James Corden has been forced to apologise for making jokes about Harvey Weinstein’s alleged sexual assault at a black-tie charity event in Los Angeles after being condemned by two of the women who have accused Weinstein of rape.

Actor Rose McGowan, who alleges that Weinstein raped her, tweeted a clip of Corden’s speech and wrote: “You motherfucking piglet.”

She said in an another tweet: “Hearing the audience’s vile roars [and] laughs show exactly what kind of Hollywood you really are.”

The Italian actor Asia Argento, who alleges that Weinstein raped her when she was 21, tweeted a video of Corden’s jokes. She added the caption: “Shame on this pig and everyone who grunted with him.”

Corden has since apologised for causing offence, and says his jokes were intended to shame Weinstein, not his victims.

In a statement released on Twitter, the British star said: “To be clear, sexual assault is no laughing matter. I was not trying to make light of Harvey’s inexcusable behavior, but to shame him, the abuser, not his victims. I am truly sorry for anyone offended, that was never my intention.”

In footage of the event, loud groans can be heard after Corden told his audience it was a beautiful night in LA – “so beautiful, Harvey Weinstein has already asked tonight up to his hotel to give him a massage”.

Corden said: “I don’t know whether that groan was that you liked that joke or you don’t like that joke. If you don’t like that joke you should probably leave now.”

Emboldened, he continued: “It has been weird this week hasn’t it, watching Harvey Weinstein in hot water. Ask any of the women who watched him take a bath … it’s weird watching Harvey Weinstein in hot water.

“Harvey Weinstein wanted to come tonight but he’ll settle for whatever potted plant is closest.”

That joke prompted more groans. “Oh come on!” said Corden.

McGowan also said that CBS, who broadcast Corden’s Late Late Show should donate to a women’s charity, or they too “support rape culture”.

Corden, the host of The Late Late Show, was master of ceremonies at the gala for amfAR, a foundation for Aids research, on Friday evening. The footage of his jokes was posted on Twitter by a Hollywood Reporter journalist, Chris Gardner.

Julia Roberts was given a special award for courage during the event while the guests included Tom Hanks, Goldie Hawn, Melanie Griffith, Sean Penn and Coldplay’s Chris Martin as a surprise guest performer.

For many on Twitter, Corden’s jokes were far too soon. “James Corden’s ‘jokes’ about the Weinstein situation are disgusting. Sexual harassment is never funny. Ever,” wrote one user.

“James Corden just embarrassed every #Brit in #LA. Whack jokes about #Weinstein & #sexualassault are no joke,” wrote another.

Weinstein was executive producer of the 2013 film One Chance, a biopic in which Corden played the Britain’s Got Talent winner Paul Potts. It was Corden who suggested Take That’s Gary Barlow to Weinstein when he needed to change the music on his stage musical project Finding Neverland.

The condemnation of Corden for making jokes followed the condemnation of Saturday Night Live over a week ago for not making jokes and for ignoring the story altogether. But on Saturday Weinstein did feature. The show included a sketch featuring a “women’s roundtable” of actors at a film festival. On the subject of whisper networks, one said: “We had a secret code among us actresses to warn each other about creeps. The code was: ‘He raped me.’ And if the men were listening, they tuned us right out.”

In the regular “weekend update” section, the comedian Michael Che said: “It’s so easy to make jokes about a guy who looks like this,” pointing to a photo. “He looks like chewed bubble gum rolled in cat hair.”

Weinstein said he has made a mistake, Che continued, but Weinstein’s actions were not a mistake. “You assaulted dozens of women. That’s not a mistake, that’s a full season of Law & Order.”