Updated

The European Union is warning Denmark its plans for customs checks may violate EU law and the Schengen free travel agreement.

Jose Manuel Barroso, president of the European Commission, telephoned Danish Prime Minister Lars Loekke Rasmussen Friday morning, then followed up with a letter saying the commission had "grave concerns" that Denmark's plan would hinder the smooth functioning of Europe's single market.

Member countries may not institute systematic border checks. They can sometimes institute spot checks, but Barroso wrote that the country must demonstrate that the measures are necessary. Denmark says the checks are needed to fight cross-border crime and tax evasion.

Barroso said the commission "will take all necessary steps" to enforce the law.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

BRUSSELS (AP) — The European Union is warning Denmark its plans for customs checks may violate EU law and the Schengen free travel agreement.

Jose Manuel Barroso, president of the European Commission, telephoned Danish Prime Minister Lars Lokke Rasmussen Friday morning, then followed up with a letter saying the commission had "grave concerns" that Denmark's plan would hinder the smooth functioning of Europe's single market.

Member countries may not institute systematic border checks. They can sometimes institute spot checks, but Barroso wrote that the country must demonstrate that the measures are necessary. Denmark says the checks are needed to fight cross-border crime and tax evasion.

Barroso said the commission "will take all necessary steps" to enforce the law.

(This version CORRECTS style on spelling on Danish premier's middle name)