In a major development, director-general of UNESCO Audrey Azoulay has asked Indian authorities to ensure timely investigation and "shed light" on the mysterious death of journalist Parag Bhuyan.

"I deplore the death of Parag Bhuyan," Azoulay said in a statement posted on the UNESCO website.

"I trust that the Indian authorities will ensure a timely investigation to shed light on the circumstances of Parag Bhuyan's death. No effort should be spared to enable journalists to exercise their profession safety, without let or hindrance," the UNESCO director-general said.

"In his work, Parag Bhuyan, an experienced journalist of the Pratidin Time group, specialized in issues relating to corruption and local crime," the statement by UNESCO, said.

In a recent letter to Assam chief minister Sarbananda Sonowala by the Editors' Guild of India, it expressed concern about the "growing incidents of violence against journalists in Assam" and also attached a list of 31 journalists who were killed in Assam since 1991.

Bhuyan was killed after being hit by an unknown car on November at Tinsukia's Kakopathar. He was admitted to Aditya Nursing Home in Dibrygarh and later succumbed to his injuries while undergoing treatment.

Following the incident, CM Sonowal ordered a CID investigation into the matter. The driver of the vehicle and his assistant were traced in Arunachal Pradesh and were arrested.