The mast went up more than 12 months ago, sparking a huge outcry as it backed onto the residential Newfields Estate, despite being on the industrial estate.
Planning permission for the mast wasn't needed as it was below 18 metres high. Instead, it was referred to planning for consideration.
The public were then meant to be consulted about the mast, but there was some misunderstanding over whether this was the responsibility of the council or Orange, the mobile phone mast provider.
Mr O'Brien said: "As far as I'm concerned it was the council's responsibility, and they failed to consult people properly. The ombudsman didn't agree with me and found in the council's favour.
"The ombudsman has found against the people, which has led me to ask who the ombudsman is answerable to.
"It appears that if someone wants to appeal against the ombudsman they have to go to the deputy ombudsman, and then to court. To my mind the ombudsman's deputy is seldom going to accuse him of wrong-doing, and ordinary people cannot afford to go to court.
"The local authority can afford to go to court, as it can use taxpayers' money to fund court visits."
Mr O'Brien questioned the ombudsman's powers in parliament last November, and will now chair the interview with the ombudsman for the North in his role as a member of the select committee responsible for monitoring the actions of the deputy Prime Minister's office.
He said: "Mobile phone masts are something which affect the whole country, not just my constituency, and I feel we all need answers about the role of the ombudsman, which is often the last resort for people concerned about them."