Hungary is ready to sue the European Commission to reimburse the costs of protecting the European Union's external border, which Budapest says has cost it some 2 billion euros ($2.20 billion), Prime Minister Viktor Orban's chief of staff said.

Nationalist Orban closed down a major transit route through Hungary for hundreds of thousands of asylum seekers fleeing war and poverty in 2015, bolstering his support at home but earning him widespread criticism from many EU allies.

"We are ready to sue the European Commission after it had reimbursed partially or in full the costs incurred by other member states protecting the Schengen border," Gergely Gulyas told a news conference on Thursday.

"Hungary has spent two billion euros on protecting the Schengen border in the past years without getting any meaningful contribution whatsoever from the EU."

Orban has displayed a sense of vindication after Germany on Monday announced plans to impose tighter checks at all of its land borders in what it called an attempt to tackle irregular migration.

The controls within what is normally a wide area of free movement - the European Schengen zone - will start on Sept. 16 and initially last for six months in a shift from Berlin's previous open-door policy.

"We can see that there are changes in Europe," Gulyas said. "In 2015 the Hungarian Prime Minister was the first to clearly say that unless the EU enforces community law and the Schengen Agreement ... then Schengen will collapse."

Gulyas said the decision by Berlin to impose border controls from Monday means that Germany was destroying the free movement area within the EU.

"First it destroyed it by not making EU member states efficiently protect the external border, and now it is destroying it by imposing internal border controls."