A woman has claimed she was subjected to a series of offensive questions about her sexual past and drinking habits after bringing an allegation of rape against a senior member of the Socialist Workers Party (SWP).

The UK's most prominent far left organisation is already facing a major showdown over previous handling of separate rape accusations against a senior party figure – identified by the party only as Comrade Delta. This weekend up to 500 members could quit the Marxist group over the alleged whitewash.

The SWP's leadership is under fire for setting up a "kangaroo court" to hear allegations of rape and sexual misconduct dating back to 2008 against the man. The allegations made at the party's disputes committee were dismissed by a panel of seven and never passed on to the police.

One alleged victim claimed that during the hearing, she was asked if she "liked to have a drink".

A transcript of the SWP's annual conference in January, leaked to the Socialist Unity blog, revealed that senior officials pleaded with hundreds of activists to trust in the committee's verdict and reminded lay members that the party had "no faith in the bourgeois court system to deliver justice".

On Sunday, scores of party members will gather in London after the leadership was forced to call a special conference to deal with the growing "In Defence of Our Party" faction which wants to challenge the way the allegations were heard and the organisation's democratic structures.

Another woman – who cannot be named for legal reasons – has told the Guardian that she also faced a welter of inappropriate questions during her own disputes committee hearing after she reported being raped by another man in the party.

The young female member in the latest case says that the senior party member had physically abused her in front of other party members. Then, she claims, in early 2011 the male organiser pressured her into meeting and then raped her in her bedroom.

She felt that if she'd gone to the authorities, she would have be expelled from the party, because of the SWP's hostility to the police. "If you go to the police you get kicked out automatically," she said.

Following the incident she quit the party but a local organiser then persuaded her to take her allegations to party's internal disputes committee.

The senior party member, who could not be contacted, has previously denied the allegations. However when she arrived at the hearing in late spring that year, she says the two judges in the case, Amy Leather and Pat Stack, were from the central committee.

She described the line of questioning during her hour long cross examination as offensive. "[They asked me] had you been drinking? … Are you sure that you said no, and are you sure you didn't consent. Was he drunk? Because it would be different if he was drunk."

She says she was also interrogated about her previous sexual history.

During the hearing two other women made allegations against the senior figure including attempted rape and sexual impropriety.

She says she was called back that afternoon and told the verdict. The committee did not rule on the truth of the rape allegation, she said.

She claims she was told the alleged rapist was going to be suspended and encouraged to read up on women's liberation. She then says she was warned against speaking about the hearing.

"They said, if you go around calling him a rapist, you'll be in trouble. If you tell anyone, you'll be in trouble … They didn't elaborate. They're not the kind of people to get on the wrong side of."

She added that she was coming forward two years later because she believes the SWP is a dangerous environment for women: "I want people to know it's a systemic thing. They've done this a few times, covered things up in the interests of the party and it's a dangerous environment to be in."

The SWP has denied a cover-up and says they do not recognise this account of the hearing.

But participants in the disputes committee hearing described the line of questioning as "disgusting" and described the suspension as a travesty. "The fact that he got basically a slap on the wrist was just appalling."

"They [the SWP leadership] are putting the interests of the party above the interests of the women … which I think gives a green light to people to behave in an appalling way to women because there's now been two signals that you'll get away with it."

Responding to the allegations of mishandling an investigation, Charlie Kimber, the party's national secretary said: "The SWP strongly contests major elements of this account of the disputes committee hearing. The woman concerned brought serious accusations to our attention, we investigated, found against the accused and took prompt action. Those are the facts of this case."

Kimber said the SWP had taken effective action but said that he couldn't go into further details as the matter was confidential.

He added: "I hope that after the party's conference [on Sunday] we can move forward united."