YEKATERINBURG, May 31. /TASS/. Search operations for a Siberian vice-governor who went missing after falling into the water during a boat trip will be suspended after dark to be resumed at dawn, a spokeswoman for the regional department of the Russian emergencies ministry told TASS on Sunday.

Vitaly Yermoshin, vice-governor of the Khanty-Mansi Autonomous Area known as Yugra, went missing after falling overboard at the 1,160th kilometer of the Ob and Irtysh River confluence during a boat trip on Saturday.

"A round-the-clock post has been set up at the river bank from among local residents, rescuers and policemen," she said, adding that by the dusk some 20 kilometres of the river banks had been surveyed with the help of sonars and a drone but to no avail.

The press service of the Yugra governor told TASS Yermoshin had heart problems and might have felt sick. The Urals transport investigation department of the Russian Investigations Committee launched a pre-investigation check. The Yugra governor, Natalia Komarova, has been informed about the accident.