Dutch finance minister Jeroen Dijsselbloem and others urged Apple to pay a bill that analysts say could reach €19 billion with interest.

The ministers are discussing ways to harmonise tax rules for international companies. Mr Dijsselbloem said that these companies "have an obligation to pay taxes in a fair way."

"International tax loopholes are a thing of the past," he added.

He said Apple will have to pay back taxes both in the United States and Europe, "so get ready to do that."

Foreign Secretary Philip Hammond, Mr Dijsselbloem's British counterpart, said the EU was keen "to make sure that international corporations pay the right tax at the right place."

"That's the fair way to do it, and we are going to make sure it happens," said Mr Hammond.

Both Apple and Ireland, Apple's European headquarters, are appealing against the decision, one of several faulting international companies for exploiting European exemptions to pay minimal taxes.

Both Starbucks and Fiat Chrysler are contesting rulings handed down last year that they are each about €30 million in arrears.

Ministers and senior EU officials in the Slovak capital also urge the Greek government to speed up enactment of economic reforms so it can get its hands on the next batch of bailout cash before the end of October.

Greece, which depends on the money due from the bailout to stay afloat, has recently fallen short of reform commitments, stoking concerns of a flare-up in the country's debt crisis.

Because it has not delivered on the reform promises it has made, it cannot yet get hold of the €2.8 billion due from this current phase of its bailout program.