Residents complain of 'severe carbon monoxide poisoning' as satellite images show blanket of smoke across eastern Siberia.
US, Dutch, Swiss, Swedish, South Korean, German and Russian tourists banned from leaving the area.
Police say he hanged himself but his grieving wife does not believe he would take his own life.
Experts say Kuzya, Borya and Ilona have adapted to life in the wild and satellite data shows they are happily roaming about their new habitats.
Horrific crash in Krasnoyarsk as Nissan hits kerb, flies into the air to hit second floor balcony, and kills father on Sunday morning walk.
Driver spots big cat at side of busy road, alerts police, and young male is tranquillised.
The Russian president's trip on Wednesday coincided with a marked improvement in levels of pollution, they claim.
Russian ecologist says his undercover trip shows Arctic ecosystem is irreversibly damaged, as whistleblower in ecological watchdog quits and leaves town.
Beijing proposes tours to neighbouring Khabarovsk region which wind the clock back to the Communist era.