BANGKOK — At least 25 people have died in severe flooding in southern Thailand since New Year's Day, leaving businesses paralyzed, schools closed and thousands of tourists stranded, the government said Tuesday.

Twelve provinces have been hit by unseasonal rains and surface runoff since Jan. 1, affecting more than 1 million people, the Interior Ministry said, adding that the main highway connecting the south with the rest of the country was swamped and impassable.

One of the main airports in the region has been closed since Friday and will be shut until at least Wednesday, while train services remain suspended. Schools have been closed since last week.

The Meteorological Department predicted more heavy rain in the region, which has popular beaches and resorts that attract millions of foreign tourists every year.