Actor Jeremy Piven has been an 'emotional wreck' in the wake of allegations he sexually abused or harassed four women, a source has told DailyMail.com.

The industry insider claims Piven broke down in tears on Wednesday during filming of his new TV series, before walking off set in front of stunned production staff.

Entourage star Piven, 52, was filming scenes for his new CBS series Wisdom of the Crowd at the TV network's studio in Los Angeles when he broke down.

The source claims the actor - who portrays Silicon Valley tech entrepreneur Jeffrey Tanner in the new drama - has appeared 'jittery' and 'stressed' as he continues to work, while privately dealing with the fallout of the allegations against him.

Rough times: Jeremy Piven is said to have been in an 'emotional wreck' at work after he was accused of

The actor was filming scenes for his new CBS series Wisdom of the Crowd at the TV network's studio in Los Angeles when he broke down in tears

Piven was accused on Twitter of sexual harassment and assault by 38-year-old actress Ariane Bellamar at the end of October who claimed the star groped her twice, once in his trailer on the Entourage set and the other at the Playboy mansion.

That was followed by actress Cassidy Freeman who said on her Instagram page that Piven engaged in 'predatory behavior' against her when she was 'far too young.'

And then two more women have since come forward accusing the Emmy winning actor of sexual assault and harassment.

Washington-based advertising executive Tiffany Bacon Scourby, 39, and Hawaii-based porn star Isis Taylor both say Piven attacked or harassed them.

Piven has denied all allegations of sexual assault saying they 'are absolutely false and completely fabricated.'

The source said: 'Jeremy is a mess, he broke down in tears as we were working on a scene and he left the set. Filming was stopped. He has become an emotional wreck within the last week as these allegations mount against him.

'Everything appears to be getting on top of him. The set has been increasingly tense.'

The source said Piven has kept 'himself to himself' since the allegations emerged with producers asking production crew to be 'sensitive' when dealing with the actor.

Actress Ariane Bellamar, (left) 38, accused the actor of groping her breasts on the Entourage set last month. porn star Isis Taylor both say Piven attacked or harassed them.

'There is a feeling that he has become paranoid. A request went around from the executives not to look at our phones when he was around. The suggestion was that he was thinking we were googling news about him or reading the allegations,' the source said.

CBS has said in a statement that it is aware of the media reports and is investigating, but for now filming continues on the show.

The source added: 'So far we were told that the series would not stop filming despite these media accusations. CBS have invested a lot of money and resources into this drama hoping it will become a long term hit.

'Before we started, the show was being heralded as the most exciting new drama for the network.

'While no-one has publicly told us that the production may be closed down, the crew are getting nervous. Jeremy's reaction did not help matters. We still have several more weeks of episodes to complete.

Advertising executive Tiffany Bacon Scourby (left) says Piven attacked her in 2003 in his hotel room and actress Cassidy Freeman (right) also accused him of engaging in 'predatory behavior' against her when she was 'far too young'

'Currently the show is ordered for 13 episodes in total, but there is talk that this show was on the block.

'The ratings were not as good as expected, and Jeremy's hopes of a new hit before these allegations looked 50/50. Our worry is that they pull us out of the deal early.'

The show is expected to go on hiatus for Thanksgiving in the next couple of days.

Piven wrote on Twitter after the allegations emerged: 'What am I not able to do is speculate as to the motivations of these women, as a human being I feel compassion for the victims of such acts, but I am perplexed as to the misdirection of anger with false accusations against me and hope they do not detract from the stories that should be heard.'

Representatives for CBS declined to comment. and Piven's rep had 'nothing to add.'