A European Union tax overhaul to raise levies on large digital firms needs a thorough debate, German Finance Minister Olaf Scholz said Saturday, although he maintained that an agreement could still be found by the end of the year.

Under a proposal from the European Commission in March, EU states would charge a 3 percent levy on digital revenues of large firms like Google and Facebook that are accused of routing their profits to the bloc's low-tax states.

The plan is opposed by smaller states like Ireland that fear losing revenues, and by Nordic governments that think the tax could stifle innovation and trigger retaliation from the United States — which is home to most of the firms that could be hit by the proposed tax.