A group of Permanent TSB buy-to-let tracker mortgage customers are to challenge a decision by the lender to terminate the interest-only period of their mortgages.

Operating under the title  "Protect Our Trackers", the group is launching an information campaign highlighting how customers are affected and informing them of their options.

The group claims that Permanent TSB's buy-to-let customers have been informed that they must change to capital and interest repayments or they will lose their tracker rate, saying that this is in line with their mortgage terms and conditions.

Dublin-based solicitors, Walter Odlum & Company has written to Permanent TSB to reinstate the terms of the loan agreements on behalf of the group. A senior counsel has also been instructed regarding the matter.

The group claims that customers face a three-fold jump in their monthly payments as a result. For example, a customer who borrowed €300,000 in 2005 over 25 years, before the latest ECB rate change, would currently pay €525 per month.

This repayment would rise to approximately €1,600, to cover both the mortgage principal and interest, should Permanent TSB's decision remain unchallenged.

The group claims that it may take the lender up to 12 months to communicate directly with affected customers, a process that commenced in November 2010.