Germany's interior minister is calling for an American effort to restore trust to trans-Atlantic ties as he meets a visiting US senator following allegations of massive National Security Agency surveillance, ABC News reported. Hans-Peter Friedrich on Monday met Sen. Christopher Murphy, a Democrat who serves on the Senate Foreign Relations Committee, along with the US ambassador to Berlin. Murphy is visiting Berlin and Brussels with two Congressmen. Germany has been angered above all by allegations that the NSA monitored Chancellor Angela Merkel's cellphone. A ministry statement said Friedrich said "special efforts" are needed from the US to restore "the necessary mutual trust." He reiterated Germany's position that spying on friends is unacceptable and said he hopes Congress will take initiatives to "prevent such incidents in future.