BERLIN (AP) — German lawmakers probing the U.S. National Security Agency following Edward Snowden’s revelations have hit a hurdle: their own government.

Officials have refused to let a parliamentary inquiry see dozens of German intelligence documents detailing the extent to which the country’s spy agencies cooperated with their U.S. counterparts.

A government spokeswoman said Friday that Germany is bound by secrecy accords that give the U.S. the right to review and comment on any documents that affect its interests.

But spokeswoman Christiane Wirtz denied this amounted to a U.S. veto.

Opposition lawmakers nevertheless complain that their work is being hampered by the people they are meant to be investigating.

Apart from the NSA’s activities, the panel is also examining whether German intelligence agencies broke the law when they cooperated with their U.S. counterparts.

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