NEW DELHI (BLOOMBERG) - Rajendra Pachauri, chairman of the United Nation's Intergovernmental Panel on Climate Change, has been accused of sexually harassing a woman colleague at a New Delhi-based research institute headed by him.

The 29-year-old researcher accused 74-year-old Mr Pachauri of making physical advances and sending lewd text messages and e-mails since she joined The Energy and Research Institute in September 2013, according to a copy of the complaint and her lawyer.

The preliminary complaint has been registered with the Lodhi Colony police station in South Delhi. If the charges are proved, Mr Pachauri may face a prison sentence of as many as five years, according to Prashant Mendiratta, the complainant's lawyer.

The woman, whose name cannot be revealed under Indian law, will appear before a Delhi court on Monday and will hand over evidence including her laptop and phone to the police, Mendiratta said.

"We have no comments to offer as the matter is sub- judice," Mr Pachauri's office said in an e-mailed statement.

The UN panel won the Nobel Peace Prize in 2007. In 2008, Mr Pachauri was awarded the Padma Vibhushan, India's second-highest civilian award.