News International had its office swept for bugs around the time of the bid by Rupert Murdoch for overall control of BSkyB, the phone-hacking trial has heard.
William Clegg QC, counsel for former News International head of security Mark Hanna, said there were a number of reasons to sweep the office for bugs. "One obviously was newspaper are very competitive with each other, and some journalists may be anxious to try to steal a scoop from a rival.
"One of the reasons for the sweeps was to avoid that possibility.
"In 2011, News Corp was trying to increase its shareholding in BSkyB, I think with the objective of becoming the majority shareholder.
"t was a sensitive topic at News Corp, and another reason why you would want to be sure discussions about such a matter were not broadcast to people who were potential competitors."
As the phone hacking scandal escalated, the rooms on the 10th floor at Thomas More Square were "masked", a reference, Clegg said, to anti-bugging activity.
The jury was told on Monday that in 2011 there was also "a perceived high security risk" to individuals including Rebekah Brooks, News International's then chief executive, as the phone-hacking scandal erupted.
The newspaper publisher brought in an outside company to provide extra security for Brooks and two other senior executives in the weeks before the News of the World closed, the hacking trial heard.
Three personal security operations were swung into action, codenamed "Blackhawk" for Brooks with two others mounted for the then general manager Will Lewis and the company's then head of communications Simon Greenberg. These were codenamed "Kestrel" and "Sparrowhawk".
The Old Bailey heard how the "security risk had never been higher" for Brooks the weekend after the News of the World closed in July 2011, with round-the-clock security provided to her homes in London's Chelsea Harbour and Oxfordshire.
Security was a "routine" issue given the competitive newspaper environment, the jury heard, and News International had the executive floor of the company swept for electronic devices at least twice that year.
The jury was shown an email from Brooks to Lewis dated 25 January 2011, and copied in to Mark Hanna, the company's head of security, which read: "Can we have my phones, and office swept … thanks. Discreetly."
Brooks's home in Chelsea Harbour and her car were also swept.
The 10th floor of News International's headquarters in Thomas More Square in Wapping, east London, were again swept in May. The jury was told of an email exchange between the head of facilities at News International and the head of security at BSkyB confirming the offices including Rupert Murdoch's office were being checked. At the time Murdoch was making a bid to take over BSkyB.
Jane Viner, head of facilities, told the court this could have been arranged on a daily basis if needed.
International Corporate Protection was contracted by News International during 2011 to provide extra security. Threatening and abusive emails directed at the executives were being received by the company and it was decided these would be intercepted by security. There were also "sporadic" demonstrations outside Wapping.
Clegg said his client has served many years in the army, including in the first Gulf war, and was responsible for security ranging the Wapping entrances and exits, to the personal safety of correspondents sent to war zones.
Hanna went to Oxfordshire to check the security at Brooks's country home on 15 July, the day she resigned and five days after News International closed the News of the World. Hanna stayed there until Sunday, the jury heard.
Before her resignation a plan had been under way to relocate her office temporarily to Oxfordshire and it would have been "routine" to assess the risk for any off-site office or meetings of executives at a time of heightened risk, the jury heard.
Hanna and Brooks have been charged with conspiracy to pervert the course of justice by concealing potential evidence from Scotland Yard detectives investigating phone hacking.
They both deny the charge.
The trial continues.
