Zagreb, September 18 (RHC)-- As thousands of refugees poured into Croatia from Serbia on Thursday, Zagreb announced that it could not take in any more migrants.

Interior Minister Ranko Ostojic said Croatia would allow refugees safe passage to reception centers around the capital, but that those not seeking asylum would be considered illegal immigrants. He added that 6,500 refugees had entered Croatia in the past 24 hours.

"Croatia will not be able to receive more people," Ostojic told reporters in the town of Tovarnik on Croatia's eastern border with Serbia. "When we said corridors are prepared, we meant a corridor from Tovarnik to Zagreb," he added, suggesting Croatia would not be allowing migrants simply to proceed northwards to Slovenia.

The developments come a day after refugees clashed with Hungarian police, who fired tear gas and water cannon to stop them from crossing the country's border with Serbia.

UN Secretary-General Ban Ki-moon on Wednesday said he was "shocked" by Hungary's actions, saying people "fleeing war and persecution... must be treated with human dignity." Germany and Austria, which have recently taken in thousands of refugees departing Hungary, as well as Slovakia have, meanwhile, re-imposed identity checks on parts of their borders, and Poland and the Netherlands are considering following suit.