The German chancellor, Angela Merkel, is coming under increasing pressure to divulge a list of targets, including the IP addresses of individual computers, that German intelligence tracked on behalf of the US National Security Agency (NSA).

Critics have accused Merkel’s staff of giving the BND foreign intelligence agency the green light to help the NSA spy on European firms and officials.

The scandal has strained relations between Merkel’s conservative Christian Democratic Union and its junior coalition partner, the Social Democrats, whose leader, Sigmar Gabriel, has publicly challenged her over the affair.

Gabriel told the German newspaper Bild am Sonntag that parliament needed to see the list, which contains names, search terms and IP addresses. The government has said it must consult the US before revealing the list, whose contents are thought crucial to establishing whether the BND was at fault in helping the NSA.

Gabriel, who is also Germany’s vice-chancellor, said: “Imagine if there were suspicions that the NSA had helped the BND to spy on American firms. Congress wouldn’t hesitate for a second before looking into the documents.”