German Chancellor Angela Merkel's government has announced a probe into ties between its secret services and US agencies following extreme pressure from the public and political rivals.

Monday's announcement was in response to a report by news weekly Der Spiegel which said documents provided by fugitive intelligence analyst Edward Snowden showed that German services closely co-operated with the US National Security Agency (NSA) and used its Internet spy software XKeyscore.

Merkel was pressed at a news conference earlier this month

Germany's domestic intelligence service, BfV, said it was only testing the Internet tool, which Der Spiegel said can store several days' worth of Internet traffic data and content as well as key words from online search engines and Google Maps.

The US documents reportedly also praised the "eagerness" of foreign intelligence service BND President Gerhard Schindler to co-operate more closely with the NSA and said the German government had modified its interpretation of privacy laws to allow more flexibility in data sharing.

Streiter defended the fact that secret services operate out of the public eye, adding that "international terrorism can only be fought through international cooperation, and this serves to protect our citizens in Germany."

But he also said that "German law applies on German soil, and that goes for everyone, including our intelligence services. That's why the government takes very seriously the questions that arise from the weekend media coverage."

"The chief of staff of the chancellery has initiated an extensive review. The outcome will shortly be reported to the Parliamentary Control Committee."

With elections due to be held on September 22, the spying scandal has put unwanted pressure on Merkel's government.

The chancellor's initial reaction to the accusations, saying that the country should wait of the US to finish its own iinvestigation, earlier this month were crticised as "clueless" by entre-left challenger Peer Steinbrueck.

Source: Al Jazeera and agencies