The News Media Association - which represents the national, regional and local newspaper and magazine industries - has called on the Independent Police Complaints Commission to reconsider its rejection of a complaint by a reporter who was issued with a harassment notice.
The frequency of Metropolitan Police press leak investigations nearly tripled in the year the Leveson Inquiry started, new figures show.
Between 2005 and 2010 there were no more than ten probes carried out by the force in any one year.
However, it 2011 - the year the phone-hacking scandal erupted and the Leveson Inquiry was started - there were 27.
A lawyer handling Press Gazette's bid to make police disclose how many times they have accessed journalists' phone records has pledged to take the case as far as the European Court of Human Rights if necessary.