Austria said yesterday it might be forced to re-instate border controls with Hungary after Budapest refused to take in asylum seekers sent to it by other European Union states.

The row between the two EU neighbours has further weakened the already fragile unity in Europe over how to share the burden of a rising tide of migrants.

Several countries on the EU’s periphery say the system for tackling migration is broken. But Hungarian Prime Minister Viktor Orban’s decision to halt transfers of asylum seekers is the most radical step taken by any European leader so far.

Orban has a history of tangling with Brussels. Meanwhile, he is under political pressure at home from an anti-immigrant far-right opposition party.

We do not rule out border controls as a last resort

Under EU rules, migrants must apply for asylum in the first member state they enter. If they move on to another EU country, they can be sent back to the country where they entered.

Hungary said it was temporarily suspending accepting such transfers back because it was overwhelmed by migrants, after 61,000 crossed into the country from outside the EU since the start of the year. That angered Austria, where many migrants head after passing through Hungary.

“Hungary’s decision is completely unacceptable for us,” Austrian Interior Minister Johanna Mikl-Leitner said on Austria’s ORF radio station, adding that “we do not rule out border controls as a last resort.”

That would involve passport checks on the Austrian-Hungarian border – something that ended when the two countries implemented the Schengen agreement on border-free travel nearly a decade ago.