In the past three to four weeks, the Ombudsman has received roughly 200 complaints about the Bank of Ireland’s decision to raise rates on certain tracker mortgages. The Financial Conduct Authority previously signalled it was neither willing nor able to take action against the bank.

An Ombudsman spokesman said each case would be looked at separately: “What we would be looking at is the individual set of circumstances for each consumer – what were they told and what was the sales process.”

Whether the complaint concerned a broker depended on how far the case rested on advice, he added.

The Law Department principal Justin Selig, who is leading a landlord class action against the rate rise, said he had sent the Ombudsman a full report of the matter, which had, as yet, not been answered.

He said: “We have been telling landlords to make a complaint and we have also been providing them with what they need to say.”

Complaining to the Ombudsman was the correct course of action, he said.

Earlier this month, MPs published a letter from FCA chief Martin Wheatley written in May, in which he suggested the FCA’s ability to take action on the issue was limited.

He added: “Customers concerned have the right to complain to the firm, to the intermediary that sold the product and, in most cases, to the Financial Ombudsman Service.”