Playmaker last month spun-off from parent Band & Brown, in a deal that sees founder Rowan Andrews become MD of the infant agency.
Playmaker has now moved into the offices of NN, a firm that supplies news and features to papers and magazines.
Andrews said the deal - which enables 30 NN staff to advise Playmaker clients on PR - would give clients 'a larger share of voice in the media'.
NN editor Richard Leifer said the deal could raise a question mark over the journalistic independence of his firm.
Under the terms of the deal, NN will take a stake in Playmaker and the agency's directors will provide advice to Playmaker clients, which include npower and CIS.
Leifer said: 'There is a potential conflict and threat to our integrity but we won't allow it to happen. If there was a chance news editors thought there was a cash reason for us putting out a story, they won't touch it - and we know that.'