Vienna, Aug 28 (IANS): A truck with Hungarian licence plate parked at the side of the highway to Vienna on Thursday morning was discovered to have dozens of dead bodies inside, police said.

The truck was captured on camera in the south of Budapest at around 3 a.m. on Wednesday and was later spotted on camera near the Hungarian side of the border with Austria at around 9 a.m. on Wednesday.

The truck was then found by police parked just outside Vienna on Thursday at around 6 a.m., but police did not investigate; the truck was finally opened at 11:30 a.m, Xinhua reported.

According to police, all the bodies were those of refugees. There were no survivors. The number of the dead had not yet been identified.

However, police estimate the death toll is around 20-50 people. The driver was not found.

The police are not sure where the refugees are from, nor do they know the cause of death, but speculated they might be from Syria or Afghanistan and could have died from lack of water or air.

A detailed report is expected on Friday.

Hungarian media reported the truck was registered to a Romanian national.

Janos Lazar, chief of the Hungarian prime minister's office, said the plates had been issued in the city of Kecskemet, about 85 km from Budapest, to an unnamed Romanian national.

The truck bore licence plate from Hungary, but Austrian police have not confirmed which country the truck is originally from.