Brussels (AFP) - Belgian prosecutors have launched an investigation into allegations of widespread surveillance by Germany, which is alleged to have helped the US spy on Berlin's allies in Europe.

"The inquiry's objective is to learn about the exact nature of the acts that may have been committed and could be prosecuted," Jean-Pascal Thoreau, a spokesman for federal prosecutors, said Sunday.

According to Belgian press reports the probe was opened on Friday.

The investigation follows reports that Germany's BND spy agency helped the US National Security Agency amass a trove of data on targets in Europe, including the French government, European Commission and Airbus Group.

Two other investigations have already been opened in Belgium on the spying claims and have been assigned to the Belgian telecom regulator and intelligence service.

"If it should emerge that the reports of wide-scale eavesdropping by the German secret services are correct, Germany will have to provide an explanation," Telecoms Minister Alexander de Croo said on Friday.

The claims -- and questions of how much the office of Chancellor Angela Merkel knew about the reported joint spying -- have occupied German politics and media for weeks, and are subject to two parliamentary inquests.

Merkel has pledged to testify before the panels if asked, while some European governments have made moves to look more closely into the claims.

According to various media reports, the snooping in Belgium took place by monitoring data carried through 15 cables, mostly operated by Proximus, the national telecom giant.