Slovenia said Saturday it would deploy soldiers to assist police "with logistics and equipment" at the border with Croatia to help tackle the influx of migrants arriving after Hungary shut its frontier.

"The army's assistance does not mean there is an extraordinary situation in Slovenia, but that the government wants to manage the situation at the border. It will only assist police with logistics and equipment," centrist Prime Minister Miro Cerar told a news conference.

At least 2,400 migrants were expected to transit through Slovenia after Zagreb began diverting the flow of thousands of people following Hungary's shutdown of the frontier.

After registering them at border checkpoints, Slovenian authorities were to transport them to the Austrian frontier from where they could continue to Germany, the preferred destination for many.

The UN refugee agency described Slovenia's handling of the border situation as "running very smoothly".

"Unlike other countries, Slovenia had time to prepare... It's not perfect, but things are moving," UNHCR spokeswoman Caroline van Buren told AFP.

The army's role in the crisis would be to provide "technical assistance, helicopter monitoring, trucks and other logistics," interior ministry spokesman Bostjan Sefic said.

"Soldiers will not have police competences," he added.

The numbers expected to enter Slovenia would be a first for the country which only saw around 3,500 migrants arrive over the past month after it reinforced border controls in mid-September.

Slovenia has said it could handle up to 8,000 refugees crossing through on their way to Austria, which has also reinforced its border ahead of the anticipated rise in the numbers.