The last surviving member of The Monkees is suing the FBI for any records it holds on the band.
Agents investigated the group over alleged anti-Vietnam War activities in 1967 and drummer Micky Dolenz claims images flashed in protest against the conflict at a gig led to the FBI's interest.
He and his late bandmates Mike Nesmith, Davy Jones and Peter Tork were also investigated for another matter that has been redacted, the lawsuit states.
Part of the FBI file on the band was released to the public in 2011, but Micky, 77, wants to see the complete case file.
A Freedom of Information Act request he filed in June failed to get a response from the FBI.
It states: "This lawsuit is designed to obtain any records the FBI created and/or possesses on the Monkees as well as its individual members. Mr Dolenz has exhausted all necessary required administrative remedies with respect to his request."
Agents kept tabs on several famous figures during the war in Vietnam, including John Lennon.
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Micky's lawyer Mark Zaid said: "We know the mid-to-late 1960s saw the FBI surveil Hollywood anti-war advocates, and The Monkees were in the thick of things.
"This lawsuit seeks to expose why the FBI was monitoring The Monkees."
The FBI has so far not commented on the move.
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