A former chair of a UN panel of climate scientists has been charged with stalking, intimidating and sexually harassing a woman who worked at a thinktank he headed for more than 30 years.

Rajendra Pachauri, 75, was accused in February last year of sexual harassment by a researcher working at Delhi-based The Energy and Resources Institute (Teri) where Pachauri was director general.

Pachauri, who quit as chair of the Intergovernmental Panel on Climate Change (IPCC) a year ago, denies the allegations.

After a year-long investigation, Indian police said on Tuesday they had sufficient evidence to file charges.

“A charge sheet was filed today in the Metropolitan magistrate court of Shivani Chauhan in Saket,” said a senior Delhi police official connected to the investigation. “Dr Pachauri has been charged with various misconduct and offences.”

The official, who declined to be named, said the charges included stalking, sexual harassment, “outraging the modesty of a woman” and criminal intimidation.

The most serious charges – sexual harassment and stalking – carry a maximum jail term of three years under Indian law.

The police official said the charge sheet ran to more than 1,000 pages and referred to SMS, Whatsapp and email correspondence between Pachauri and the researcher, who was 29 at the time the complaint was filed.

It also included the testimony of 25 witnesses, many of them past or present employees at Teri, the official added.

Pachauri’s lawyer Ramesh Gupta said his client was being vilified and could not be arrested because he had been granted anticipatory bail by a court, which means police cannot take him into custody for now.

He said the court would convene on 23 April to decide whether to extend the anticipatory bail or withdraw it.

“My client is innocent in the case. He has not committed any offence,” Gupta said. “I have not seen the charge sheet. As soon as I will see it, I will decide the next course of action.”

The woman, who has resigned from Teri, claims Pachauri began harassing her via email, Whatsapp and text messaging soon after she joined the non-profit thinktank in September 2013. She said Pachauri persisted despite her requests that he stop.

An internal inquiry committee at Teri found Pachauri guilty of misconduct and the organisation has removed him as director general. Last month, however, he was appointed as the thinktank’s executive vice-chairman.

Pachauri, who quit the IPCC over the allegation, has accused the complainant of using the media to sensationalise the case.

He received the Nobel peace prize in 2007 on behalf of the IPCC, which jointly won along with Al Gore for its scientific assessment of the risks and causes of climate change.