Five hundred female college students from Haryana's Sirsa have written to Prime Minister Narendra Modi's office, and Chief Minister ML Khattar, to accuse a professor at the Chaudhary Devi Lal University of sexual harassment and demand his suspension, as well as an inquiry led by a retired High Court judge.

Copies of the letter have also been sent to Vice Chancellor Dr Ajmer Singh Malik, Haryana Governor Bandaru Dattatreya, Haryana Home Minister Anil Vij, and National Commission for Women Chairperson Rekha Sharma, as well as senior state government officials and select media organisations.

The letter accuses the professor of "filthy and obscene acts". According to the letter, he calls girls to his office, takes them to a bathroom, and "touches private parts, and (does) obscene things with us". The girls said that when they protested, they were threatened with "very bad" consequences.

The letter claims this has been going on "for many months" and, "... because he gives a false impression of a person of high character", the professor in question has never been held accountable.

A special investigation team (SIT) to probe the matter, police said. "We immediately constituted the SIT under IPS officer Deepti Garg. (The SIT) is taking statements. It has already taken statements from many people," Additional Director General of Police Shrikant Jadhav said.

The SIT has already visited the university and statements are being taken, he said.

The girls also claimed the Vice Chancellor, rather than come to their aid, "threatened to expel us... because this professor is a person of immense political influence..." The Vice Chancellor also reportedly tried to suppress the allegations by offering the girls better marks in written and practical examinations.

The university's Registrar, Dr Rajesh Kumar Bansal, confirmed receipt of the anonymous letter. 

"The police are investigating... the university has its own committee which is probing the allegations. This is a serious accusation... there is no name on the letter but we will investigate this," he told NDTV.

"Action will only be taken afterwards. Whoever is guilty will not be spared but if someone is innocent then their character should not be assassinated," the Registrar said.

Dr Bansal said relevant CCTV footage had been handed over to the police. However, the letter claims the accused professor has already "deleted... his indecent actions from CCTV footage of his office". 

In their letter the girls - who said they had chosen not to reveal their identities fearing "dishonour" to their famlies - said they do not expect action against the professor till the university is "forced" by public opinion. The letter also calls for an investigation by a retired High Court judge.

Senior Sirsa police official Deepti Garg told NDTV the investigation is ongoing, and that statements of some of the students had been recorded. The accused professor has also been questioned, Ms Garg said, noting that a case will be filed if a preliminary inquiry finds enough evidence.

This letter comes months after the principal of a government-run school in Haryana's Jind district, was dismissed from service after being arrested for sexually assaulting girls under his care.