Ratan Tata, chairman emeritus of one of India's biggest conglomerates, Tata Sons, is in critical condition in intensive care at a Mumbai hospital, two sources with direct knowledge of the matter said on Wednesday.

Tata, 86, said on Monday he was undergoing routine medical investigations due to his age and related medical conditions.

A representative for Tata did not immediately respond to a request for an update on his condition on Wednesday.

In a statement published on his social media profiles on Monday, Tata said he remained in good spirits and that there was no cause for concern.

Tata became chairman of the autos to steel conglomerate in 1991 and ran the group founded by his great-grandfather more than a hundred years ago until 2012.

He founded telecommunications company Tata Teleservices in 1996 and took IT company Tata Consultancy Services public in 2004.

After stepping down, he was conferred with the title of chairman emeritus of Tata Sons, Tata Industries, Tata Motors, Tata Steel and Tata Chemicals, the company website says.