Merkel calls for EU data law after US spy affair

"We have a great data protection law here in Germany, but if Facebook is registered in Ireland, then Irish law applies. So we need a unified EU regulation," she said.

Talks on renewing EU data protection rules have stalled precisely because member states are unable to agree on this matter, the chancellor added.

She also said that her government prefers to wait and see what the verdict of the European Court of Justice is on a controversial EU law obliging telecommunication companies in member states to store phone and internet data for at least six months.

Germany has not implemented the law because its top court ruled it was disproportionate.

"We are open, if changes are needed to this law, they have to be done. The bigger issue however is what happens to data outside our jurisdiction," Merkel said.

The revelations that a large secret surveillance programme run by the US government tapped into the servers of companies such as Facebook has put pressure on Merkel to show some initiative ahead of general elections in September in a country where data privacy is more sensitive than in other EU states.

"We are inquiring whether the US has broken German law. So far, there is no evidence in this regard," Merkel said, while adding that secret services in Germany and the US have a long tradition of cooperating with each other.

"The end does not justify the means. We expect a clear commitment from the American government for the future that they will stick to German law on German territory," the chancellor said.

"We have to be able to rely on each other."

Her interior minister, Hans-Peter Friedrich, was in Washington last week to seek clarifications. But he was immediately criticised by the opposition as "immensely naive" and as failing to stand up to the Americans.

Earlier on Sunday SPD chancellor candidate Peer Steinbrueck accused Merkel of breaking her oath of office over the spy affair.

"Merkel swore the oath of office to protect the German people from harm. Now it emerges that German citizens' basic rights were massively abused," Steinbrueck told Bild am Sonntag.

Meanwhile, the Green and leftist opposition is calling for a standing committee in the German Parliament to investigate how the German secret service, the BND, fed its US counterpart with data, as revealed by the fugitive whistleblower Edward Snowden.

The issue is likely to have an impact on the 22 September elections. The latest polls show Merkel's Christian Democrats have lost 1-2 percentage points over the handling of the affair. But they still have a comfortable lead (41%) over the Social Democrats (26%).