"Immediately after the tremors in Irkutsk, there were cuts in electricity, mobile connections and the Internet, banks postponed work. Some houses lost roofs," the state-run RIA news agency reported from the city. "There were no victims," a spokesman for the local Emergencies Ministry told Reuters.

He said the epicentre was around 30 km (20 miles) northeast of the town of Baikalsk and the quake struck at 1035 local time (0135 GMT).

The spokesman said that on the Richter scale, the tremor measured an intensity of nine, although both the Hong Kong Observatory and the United States Geological Survey recorded it as measuring 6.3.

"There were no reports of serious destruction or casualties, thank God," the local official said, adding that buildings in the region were designed to stand even stronger tremors.

The Emergencies Ministry spokesman said that close to the shore of Lake Baikal, where a major pulp and paper plant is located, the tremor measured eight on the Richter scale.

Work at the plant, which environmentalists want closed, was suspended for an hour for safety checks, but had now resumed, said the spokesman. (Reporting by Tatiana Ustinova; writing by Conor Sweeney; editing by Andrew Roche)