The death toll from days of heavy rains and flooding in Slovenia has climbed to six, media reports said Monday, as clean-up operations continued with help from neighbouring countries.

Prime Minister Robert Golob has described the torrential rains and severe flooding that hit the Alpine country of two million as its worst natural disaster since independence three decades ago.

Flash floods and landslides that began Thursday had submerged large swaths of central and northern Slovenia, cutting off access to villages and disrupting traffic.

On Sunday, emergency workers recovered the body of a 35-year-old man in a river near the village of Mirna Perc in the east.

Another man, who was taking part in the clean-up operations, was found dead after falling into a cesspit near the town of Kamnik close to Ljubljana, media reports said.

Police did not immediately confirm the reports when contacted by AFP.

The bodies of two Slovenians and two Dutch citizens had been found earlier.

On Monday, rescue workers tried to reopen roads to the most remote or isolated places, while assessing damages when the government has said could exceed half a billion euros.

Harrowing accounts have emerged of rescue workers and volunteers helping to save locals and tourists from the floods, and sheltering them in community halls and other places.

Slovenia, an EU member, has asked for help from the bloc, seeking in particular heavy machinery such as excavators and prefabricated temporary bridges to deal with the aftermath of the flooding.

Slovenia has also asked NATO to provide transport helicopters and soldiers to help with the recovery efforts.

A first truck with humanitarian help and food arrived from Hungary late Sunday, followed by a helicopter, while Croatia provided a military helicopter to help close and secure a broken levee on the Mura River.

German Chancellor Olaf Scholz said his country was sending emergency workers, expressing "dismay" at the "terrible flood catastrophe in Slovenia and Austria".

In neighbouring Austria, the body of a man was recovered on Sunday from a river in Carinthia state, with heavy rains causing flooding and landslides in the south.