The professor, who is also a fellow at Harvard, has been arrested on suspicion of rape and sexual assault.
He has been placed under police protection and is being monitored by police.
Professor Arc was last month charged with two counts of rape, two counts each of sexual assault and sexual interference.
His lawyer, Peter Cohen, said he is cooperating with the investigation.
The professor, from Cambridge, has also been placed on a restricted list of academics and cannot leave the United Kingdom, where he has been a lecturer for the past 20 years.
Professor Cohen said he was being watched and questioned by police and that he was not a threat to the public.
“Professor Arc is not a violent person and I have not seen him in a violent situation,” he said.
However, he said the charges against him were a “huge red flag” because of the nature of the allegations.
“The most dangerous thing about these allegations is that they are totally unfounded and untrue,” he added.
Professor Arc’s accuser, an undergraduate student, told the BBC that she was in a consensual relationship with Professor Arc when he allegedly forced himself on her at the University of Cambridge in 2014.
She said that she felt “frozen”, but said Professor Arc also forced himself into her vagina while she was unconscious.
In an email, a spokesman for the University said that the allegations had been investigated by a committee which “found that Professor Arc is the victim of an incident that has not taken place”.
“We have taken action against him to ensure he is treated fairly and fairly treated,” he continued.
After the alleged attack, the university said that it had launched an internal investigation into the matter.
Later in June, the Cambridge University Association issued a statement saying it was aware of the alleged incident and had launched a review into how it dealt with such allegations.
“We are working closely with the university and will respond to the review, if appropriate,” it said.
Professor Alan Evans, of the British Association for Sexuality Education and Research, said Professor Arch had been “saddened” by the allegations, and said he had been subjected to a “torturous process” by police in the past.
Prof Evans said that, when he heard of the allegation, he took the case to the Police and Criminal Evidence Service, which he said was investigating the matter in an “independent and impartial way”.
Professor Evans said: “The university is aware of all the allegations of rape that have been made against Professor Arc, but they have not made any formal investigation of them and are not aware of any such allegation against him.”
“They will be investigating it as an allegation and they will also be taking whatever action is appropriate.”
Professor Evan added that Professor Arch was “under no illusions” that he would be prosecuted, given his position.
“What he’s said is that he is innocent, that there is no evidence to support it, and the university will take whatever action they need to take to protect him and to get justice for him.”