Campbell played for Portsmouth for three seasons before leaving at the end of last season and has returned to his former club Arsenal after a brief spell at Notts County.
Portsmouth are facing a winding-up order in the High Court from the British government's Revenue and Customs department for unpaid taxes and according to their Statement of Affairs, handed in to court last week, are some 70 million pounds in debt.
Campbell told The Times he was justified in seeking what Portsmouth owed him.
"As far as I see it, if you have a contract, you have a contract. That's it and it's only fair," the 35-year-old former England defender said.
"If you get something written down, then that is what you are owed. How's that going against football? I signed that contract in good faith.
"Some of the other players have got contracts and they've not been paid either. It's clear, it's stated, it's in people's faces. I'm not exactly going to be the one that brings them down."
Campbell, who scored for Arsenal on his first appearance in the Champions League for four years in their 2-1 defeat at Porto on Wednesday, also said he believed he could continue playing at the top level for possibly another three years.
"I think I can keep myself fit and play top football for the next two to three years," he said. "This season and at least another two. I'm here for six months, and if something happens, something happens.
"If not I'll have to look elsewhere. The manager (Arsene Wenger) has told me I've got to the end of the season and he's looking for other players, but I want to play as many games as possible for Arsenal and help them to win something."
