US online retailer Amazon, search engine giant Google and social network Facebook will testify at the European Parliament next week on the issue of tax breaks for big businesses, officials said Wednesday.

Amazon is currently under investigation by Brussels for its sweetheart tax deals with Luxembourg. The "LuxLeaks" scandal that emerged a year ago has put the spotlight on the subject.

Representatives from 11 out of 13 companies invited by the parliament will attend next Monday, parliament officials said.

The others are Coca-Cola, McDonald's Europe, Ikea, Philip Morris, Disney, AB InBev, HSBC and Barclays.

Retail giant Wal-Mart refused while Fiat did not reply, officials said.

The EU launched a series of probes last year following the LuxLeaks affair, which revealed that top global companies had negotiated lower tax rates, in some cases as low as one percent, in secret pacts with Luxembourg.

Last month Brussels ordered Starbucks and Fiat to each repay up to 30 million euros ($34 million) in back taxes for deals they had with the Netherlands and Luxembourg, respectively.

Decisions on Apple and Amazon are pending.