Croatia has closed seven of the country’s eight border crossings with Serbia “until further notice” following a massive influx of asylum seekers.

“Traffic is banned on the border crossings of Tovarnik, Ilok, Ilok 2, Principovac, Principovac 2, Batina and Erdut,” the interior ministry said in a statement.

More than 11,000 asylum seekers have entered Croatia from Serbia since early Wednesday (local time), the ministry said.

• Refugees doused in tear gas during border clash
• European refugee crisis explained
• Russia will continue Syrian campaign

The asylum seekers began heading for Croatia after Hungary sealed its border with Serbia earlier this week, cutting off a key route into the European Union used this year by more than 200,000 people, many of them fleeing violence in the Middle East and Afghanistan.

Croatia had said it would let people pass through freely on their way to other EU countries, but Prime Minister Zoran Milanovic warned his country’s resources for dealing with the influx were “limited”.

Piling on the pressure, Slovenia announced late on Thursday that it had stopped a train from Croatia, saying some 150 passengers would be returned to Zagreb because they did not have the necessary documents for onward travel.

Red Cross hand out water to refugee children. Photo: Getty

“During a regular border control of the train… it was established that 150 out of the 300 passengers did not meet the requirements for entering Slovenia,” Slovenian border police spokesman Anton Stubljar told journalists.

Their return to Zagreb would be organised as soon as possible, he added.

The asylum seekers, who were not allowed out of their carriages at Dobova station, voiced their dissatisfaction from the train windows, some of them shouting at nearby police officers who were patrolling with dogs.

At one point, the asylum seekers started to chant “UN, UN” and tapped against the windows with their hands, before the situation calmed down.

Slovenian state radio reported that an additional 16 police vehicles had been deployed near Dobova railway station.

Slovenia later suspended all train traffic between Slovenia and Croatia until Friday morning, Slovenian news agency STA reported.

Mr Stubljar also said that in three separate cases on Thursday another 24 people had attempted to enter Slovenia at the nearby border crossing of Obrezje but were also sent back.

Slovenia has been preparing for a possible influx of asylum seekers looking for a route into Europe’s borderless Schengen area.