OSLO (Reuters) - Norway evacuated thousands of people as rivers swelled to their highest levels in at least 50 years on Wednesday and homes and businesses were submerged or swept away by landslides.

Major roads were closed and train services suspended across wide parts of southern Norway as rivers breached their banks, and authorities warned of more flooding to come in the days ahead as the water moves towards lower-lying coastal regions.

Innlandet county, one of Norway's worst hit areas, said many people were isolated by the floods and that first responders may not be able to reach those in need.

"We're in an emergency situation of national dimensions," Innlandet Mayor Aud Hove said in a press release.

The government on Wednesday decided to mobilise more helicopters to take part in the evacuation, the ministry of justice and public security told broadcaster TV2.

No deaths have so far been recorded from the disaster, Norwegian authorities have said.

Strong winds, intense rain and landslides hit different parts of the Nordic region in recent days, knocking out power lines in Finland, flooding villages in Norway and Sweden and bringing public transport to a standstill in hard-hit areas.

On Monday, a Swedish train derailed when a railway embankment was washed away by floods, injuring three people.

Authorities in Norway and Sweden maintained red alerts, their most severe flood warnings, for several regions on Wednesday.

(Reporting by Terje Solsvik; Editing by Alexandra Hudson)