At least 11 people are reported to have died on Saturday and several others were injured when a Polish bus bound for Zagreb veered off the highway in northern Croatia, the interior ministry said.

"According to preliminary information, 11 people were killed and several others were injured when the bus registered in Poland deviated from the road," the Croatian ministry said in a tweet, without specifying the nationalities of the victims.

"A serious accident took place around 5:40 a.m. (3:40 a.m. GMT). The bus deviated and fell into a ditch off the highway," police spokesman Marko Muric told Agence France-Presse (AFP).

The crash occurred about 60 kilometers (40 miles) from Zagreb on the A-4 highway, which is busy during the peak of the tourist season.

Croatia has attracted hordes of tourists this summer, drawn to its stunning Adriatic coast.

Rescue teams were sent to the location of the accident, Croatian media reported. No other details were immediately available.