Police officers investigating phone hacking viewed the inquiry as "a bit of a jolly" and were excited about meeting celebrities, a senior detective has claimed.
Detective Chief Inspector April Casburn, of Hatfield Peverel, told Southwark Crown Court that she feared that her colleagues thought the investigation would be "a bit of fun".
She is accused of misconduct in public office for allegedly offering information to the News of the World in September 2010, when she was working in counter-terrorism managing the National Terrorist Financial Investigation Unit.
Casburn, 53, told jurors today she felt resources meant for fighting terrorism should not be diverted.
She said: "I felt very strongly that we shouldn't be doing hacking.
"Our function was to prevent terrorist attacks and I was particularly worried that the behaviour of my colleagues was such that they thought it was a bit of a jolly.
"They thought it was all going to be a bit of fun, getting to travel, getting to see famous people.
"I felt sufficiently strongly we should not be diverting resources which are to do with saving people's lives. It made me really angry."
At a meeting held the day before she called the newspaper, there was "palpable excitement" about who would meet Hollywood actress Sienna Miller, she said.
There was also some uncertainty over the legal position on phone hacking and whether criminal prosecutions could be brought, the court heard.
But Casburn did not feel able to speak out against the plans for the phone-hacking investigation, which had been re-opened by then assistant commissioner John Yates, she told the court.
Casburn admits making the phone call to the News of the World, but denies misconduct, asking for money and offering information that was not already in the public domain.
The trial continues.