The former chairman of a United Nations climate change panel has been ordered stand trial on charges of sexual abuse and harassment of a female colleague.

A Delhi court on Friday said there was prime facie evidence to charge Rajendra Pachauri, 78, with sexual harassment and two offences of intending to outrage the modesty of a woman.

Pachauri, who was head of the UN Intergovernmental Panel on Climate Change (IPCC) when it was awarded the Nobel prize in 2007, denies any wrongdoing.

The former UN climate chief resigned from the IPCC in 2015 when the alleged victim registered a complaint against him.

The woman reportedly told police Pachauri had flooded her with offensive messages, emails and texts and made several “carnal and perverted” advances over the 16 months they worked together at the Energy and Resources Institute (Teri), a Delhi-based energy and environment research centre Pachauri led for more than three decades.

An international investigation by Teri into the complaints questioned more than 50 employees and concluded the woman’s claims were “valid”. Pachauri has challenged the investigation and a tribunal has stayed Teri’s findings.

Pachauri claimed that text messages and emails submitted by the woman to police had had been tampered with by “unknown cyber criminals”, but police last year found no evidence of tampering.

The complainant, who was 29 at the time of the alleged offences, said she was pleased the case would proceed to trial after so long.

“[I am] chuffed to bits,” said the woman, who cannot be named for legal reasons. “This has not been easy”

Pachauri’s lawyer, Ashish Dixit, told the Guardian was a “major victory” for his client because the court had dropped four other charges, including stalking and intimidation

“The majority of the charges have been dropped by the court on it own, so it’s big step forward,” Dixit said.

The charges will be formally read to Pachauri on 20 October.

Two more women have publicly alleged Pachauri sexually harassed them while they worked at Teri, one of them claiming in a 2016 television interview that police had failed to record her statement despite repeated requests.

In April 2016 Pachauri sued one of the two women and her lawyer for defamation. The trial is still being heard.

Pachauri denies both women’s accusations.