A top United Nations climate change official has pulled out of a key meeting in Kenya next week as Indian police investigate a sexual harassment complaint against him, officials have said.

Rajendra Pachauri, chairman of the Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC), withdrew due to "issues demanding his attention", the UN body said in a statement late Saturday.

The allegations come at a crucial time as Pachauri tries to set the table for a key climate change summit in Paris in December where world leaders are expected to broker a global treaty on tackling global warming.

The IPCC said Pachauri had informed them "that he will be unable to chair the plenary session of the IPCC in Nairobi next week because of issues demanding his attention in India".

Delhi police said Pachauri, 74, is accused of sexually harassing a 29-year-old female researcher from his Delhi-based thinktank The Energy and Resources Institute (TERI).

"A lady had lodged an FIR (first information report) against him (Pachauri) for sexual harassment... about a week ago and the matter is under investigation now," Delhi police spokesman Rajan Bhagat told AFP on Sunday.

The female employee, who cannot be named for legal reasons, has accused Pachauri of repeated inappropriate behaviour, including through emails, text and WhatsApp messages, according to police.

Pachauri, a leading voice on the dangers of climate change, has denied any wrongdoing, saying his emails and mobile phone were hacked.

The climate pact he is trying to help broker seeks to limit any increase in global temperatures to just two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels.

- Catastrophic risks -

Scientists warn, however, that current trends in greenhouse gas emissions put the planet on track for double that or more, with the risk of catastrophic drought, storms and floods as well as rising sea levels.

Another Delhi police official said on Sunday that Pachauri will "most likely appeal for anticipatory bail tomorrow at a lower court", after the Delhi High Court last week granted him "interim protection" from any arrest until Monday.

"He needs to be in Delhi to seek bail," the police official told AFP, speaking on condition of anonymity as he was not authorised to speak to media.

Pachauri's office did not immediately respond to AFP's calls for comment.

An economist and industrial engineer by trade, the veteran climate change expert took the helm of the IPCC in 2002 and was elected to a second term in 2008.

The IPCC won the 2007 Nobel Peace Prize, along with former US vice president Al Gore, for galvanising international action against climate change.

But its image was then dented by several hitches that were found in one of its major reports, providing ammunition for sceptics who say the IPCC is flawed or biased.

A prediction in the report that global warming would melt away the Himalayan glaciers that provide water to a billion people in Asia by 2035 has been dismissed by glaciologists as preposterous.

Pachauri has also previously been in the limelight for authoring a racy novel which dished up sex, reincarnation and a real-life Hollywood actress.