BERLIN — U.S. contracting companies such as Cisco, which manages much of the German armed forces' data, should be contractually barred from passing sensitive information to the U.S. security services, a spokesman for Chancellor Angela Merkel's conservatives was quoted saying.

German news magazine Focus on Saturday cited Hans-Peter Uhl, parliamentary spokesman on interior policy for the conservatives, as saying Cisco needed to be required by contract not to pass sensitive material to the U.S. National Security Agency (NSA).

He said the German government wanted to monitor U.S. contracting companies more closely in future.

A spokeswoman for the German government declined to comment on the Focus magazine report.

Reports earlier this year that the NSA had tapped phones and emails in Europe, including Merkel's mobile phone, caused outrage in Germany, where memories remain of eavesdropping by the Stasi secret police during communist rule in East Germany.

U.S. President Barack Obama on Friday tried to strike a middle ground on questions about surveillance practices by the NSA, saying some checks were needed on the system but "we can't unilaterally disarm."