The high court has been told that phone hacking was widespread at the Sun, despite strong denials from Rupert Murdoch’s News UK that the daily tabloid newspaper was involved in any illegal activity.

A lawyer representing alleged phone-hacking victims also requested the historic expenses receipts of serving Sun reporter Nick Parker, in order to investigate whether his purchase of top-up vouchers for a burner mobile phone was related to the interception of voicemails.

News UK declined to comment on any of the claims in court and has always strongly denied that any illegal activities took place at the Sun. The newspaper has always denied any involvement in phone hacking or wrongdoing by senior executives and said the illegality was confined to the News of the World, its defunct sister title, which was closed down in 2011 at the height of the scandal.

Parker, who is the Sun’s chief foreign correspondent, was handed a suspended sentence in 2014 after being convicted of handling a Labour MP’s stolen mobile phone but was welcomed back to the newspaper the following year.

The high court also heard that Elton John and his husband, David Furnish, were close to settling a phone-hacking claim with the publisher of the Sun and the News Of The World, just weeks before the case was due to go to trial.

The court was told that the couple were close to reaching an agreement with News Group Newspapers, part of the wider News UK group, in a move that could avoid a high-profile trial over claims journalists at the Sun were involved in illegally obtaining voicemails, allegations the newspaper has always denied. The singer’s solicitor did not return a request for comment on whether a deal had been reached.

News UK has settled dozens of cases in recent years with confidential settlements thought to be worth millions of pounds, with agreements often reached on the eve of trial. The settlements do not accept any wrongdoing on the part of the Sun relating to the interception of voicemails.

Barrister David Sherborne told the court that two other “big ticket” claims have still yet to settle and are still due to go to trial on 4 February, which could potentially force senior Murdoch executives to appear in court. One case involves Liz Hurley and the other involves Heather Mills, who is the ex-wife of Paul McCartney, and her sister Fiona Mills.

Sherborne also claimed at a pre-trial hearing that News Group Newspapers frustrated attempts to obtain material relevant to the case. The legal proceedings are still ongoing more than seven-and-a-half years after the News of the World closed following Guardian revelations about phone hacking that led to the conviction of Andy Coulson, the former News of the World editor and Downing Street communications chief.

Many of the claims of phone hacking still winding their way through the legal system relate to the sources of news stories published in the mid-2000s, with Murdoch’s company having settled more than 1,000 civil claims for phone hacking.

Last year another group of claimants, including the former boxer Frank Bruno, settled their cases against the newspaper group.

News Group Newspapers recorded a loss of £91m in the 2017 financial year, with the accounts stating that one-off costs included significant legal fees in relation to ongoing legal issues.

The publisher of the Mirror has also made multiple settlements with celebrities over alleged phone hacking, including with the actor and press reform campaigner Hugh Grant. The publisher admitted last year it “actively turned a blind eye” to the practice over many years.