An Amazon Echo Dot is displayed during a program announcing several new Amazon products by the company, Wednesday, Sept. 27, 2017, in Seattle. (AP Photo/Elaine Thompson)

BRUSSELS - The European Union ordered the world's largest online retailer Amazon on Wednesday to pay back about 250 million euros ($294 million) in taxes to Luxembourg, saying it had been given an unfair tax advantage from 2003.

"Luxembourg gave illegal tax benefits to Amazon. As a result, almost three quarters of Amazon's profits were not taxed," European Competition Commissioner Margrethe Vestager said in a statement.

The 250 million euros is less than an estimate of 400 million which sources told Reuters last year that Vestager had calculated at that time. However, the Commission added that the exact amount of back-payment would still need to be calculated by Luxembourg authorities.

Amazon is the latest big U.S. multinational company to be reined in by the EU competition regulator, which also told technology group Apple pay back arrears of up to 13 billion euros ($15.3 billion) to Ireland. ($1 = 0.8506 euros).