Mukesh Ambani, the world's richest energy billionaire and head of Reliance Industries, has dropped out of a business delegation accompanying Prime Minister Narendra Modi on his visit to Japan. Ambani, who was to be part of a group of industrialists accompanying Modi on his first major bilateral visit, outside the sub-continent, sent regrets, government sources said.

While the sources gave no reasons for the move, an RIL spokesperson said: "Due to prior business commitments that need his presence, Mr Ambani will not be travelling to Japan."

Adani Group Chairman Gautam Adani, Sunil Bharti Mittal of Bharti Enterprises, Essar Group head Shashi Ruia, Wipro Chairman Azim Premji and ICICI Bank chief executive Chanda Kochhar were among the industrialists who are to travel to Tokyo to participate in the meeting of India-Japan Business Leaders' Forum on September 1.