The Sun is being sued for £50,000 over claims a journalist from the paper copied text messages from a stolen mobile phone.
The mobile allegedly found its way into the hands of a Sun journalist in 2009.
According to a High Court claim form, the phone was returned to the individual who had lost it by a Sun journalist who left a note inviting them to get in touch over certain "matters of interest".
The claimant initiated the legal action after being told in July 2012 that transcripts of text messages were found on a computer belonging to a Sun journalist.
A News International spokesperson said: "While this issue is subject to legal proceedings it would be inappropriate for us to comment."
In March, Labour MP Siobhain McDonagh accepted "very substantial" damages and a public apology at the High Court from The Sun.
The court heard that in October 2010 her private mobile telephone was stolen from her car in south west London.
David Sherborne, representing the MP for Mitcham and Morden, told Mr Justice Vos that in June last year police notified her that they had "obtained evidence that The Sun newspaper had accessed her text messages from about October 2010 and therefore appeared to have accessed and/or acquired her mobile phone".
A QC told the court on behalf of the newspaper that it was accepted that Ms McDonagh's mobile phone "should not have been accessed and used and furthermore accept that there has been a serious misuse of her private information".
More than 20 Sun journalists have been arrested over the last two years, mostly over allegations of bribery involving public officials. Five senior Sun journalists have been charged so far and are facing trial.
Sun Royal correspondent Duncan Larcombe and executive editor Fergus Shanahan appeared at Westminster Magistrates' Court last week accused of conspiracy to commit misconduct in a public office.
Larcombe, 37, of Aylesford, Kent, is alleged to have paid more than £23,000 to an army sergeant and his wife.
Shanahan, 58, from Felsted, Essex, is separately charged with conspiring with a public official and a journalist to commit misconduct in a public office.
Sun deputy editor Geoff Webster has been charged with authorising two payments to a public official totalling £8,000.
Chief reporter John Kay has been charged alongside former Sun editor Rebekah Brooks with conspiring to pay ministry of defence employee Bettina Jordan Barber £100,000 between 2004 and 2011.
Defence editor Virginia Wheeler has been charged with making payments totalling £6,450 to a serving police constable in the Met Police between 2008 and 2011.