Police chiefs have admitted authorising the secret recording of at least one meeting involving the friend of murdered teenager Stephen Lawrence, his lawyer said.
Duwayne Brooks met Deputy Prime Minister Nick Clegg at his Whitehall office to discuss claims that the meetings were bugged.
It has been alleged that Mr Brooks and his lawyers were invited to meetings with police in 1999 or 2000, and that officers were given authorisation to use bugs.
Speaking outside Mr Clegg's office, Mr Brooks's lawyer Jane Deighton said evidence of the covert recording was of "immediate concern".
"We told the Deputy Prime Minister that it was untenable for any government not to do everything it could now to secure the quickest and the most thorough, and the most transparent, investigation into these allegations of police misconduct," she said.
"Duwayne was very pleased that the Deputy Prime Minister agreed that he was committed to ensuring an investigation that Duwayne himself had confidence in. We are going to discuss and liaise with the Deputy Prime Minister's office next week about the details of that investigation.
"But there was one matter of immediate concern to Duwayne and that's the allegations that he's had, that the police authorised the covert recording of his meetings with me and the police in my former offices. That is of immediate concern to Duwayne.
"The deputy assistant commissioner of the police has confirmed that there are documents evidencing at least one such authorisation. We believe there are more.
"We have asked the deputy assistant commissioner for the immediate disclosure of those documents. Those documents are ones that Duwayne really wants to see and he wants to see them now, and he sees no reason why he shouldn't see them now.
"Duwayne was also very pleased that the Deputy Prime Minister has agreed to raise the issue of the immediate disclosure of those documents with the Home Secretary."