The AIB banking group has been accused of playing Big Brother with its customers after it emerged that it spies on customers' social media accounts.

This means the lender is trawling through Facebook, Twitter, YouTube and other social media accounts held by customers for comments on its service.

The bank tells customers that the move "helps us understand your behaviour".

As part of the mortgage application process, customers are now required to sign a consent form, which gives permission for a range of things, such as a credit check, to be carried out on them and to allow their social media accounts to be looked at by the bank.

It applies to those seeking mortgages with AIB and its subsidiaries, EBS and Haven. AIB Group is 71pc-owned by the State and is the Republic's biggest mortgage lender.

Mortgage broker Karl Deeter accused the bank of invading the privacy of customers by spying on them.

He said: "I'm confident that people would not be comfortable knowing that the bank can play Big Brother with their social media information."

Mr Deeter, of Irish Mortgage Brokers, said it wasn't clear if someone who posts on Facebook that they attend the likes of anti-eviction protests would end up having a mortgage application refused if the bank was to see this.

He said mortgage borrowers could not tell the bank not to examine their social media accounts if they wanted to be approved for a loan.

"You can't opt out, so what do you do?"

He said other lenders did not have similar provisions in their mortgage consent forms.

In that form, a section headlined 'Data Analytics' states: "We analyse the information that we collect and hold on you through channels, such as social media networks (Facebook, Twitter, YouTube etc.).

"This helps us understand your behaviour, our relationship with you and also our position in a market place. Our analysis helps us to offer you products and services content we believe will be of interest to you."

The consent forms for AIB, EBS and Haven also allow the lenders to carry out credit checks on customers and warn that the mortgage could be transferred or securitised.

However, data-privacy expert Daragh O'Brien said AIB should be a lot more explicit about how it is going to use the information. He said there should be an opt-out option and questioned if the move was in line with data-protection laws.

Mr O'Brien, of Dublin data firm Castlebridge, said customers had a right to be excluded from any analysis of their online data.

"AIB should put more information out, explaining what it is doing. It is failing the 'surprise the customer test'.

"This means that if the customer is surprised, you have done something wrong."

AIB Group defended the move to seek consent to inspect social media accounts. It insisted that it complies with all data-protection requirements.

"We use personal information provided on AIB Group social channels solely to respond to and deal with customer comments or queries or for such other purpose for which it is provided," a spokesperson said.

It said that in line with common practice, it engages in what it calls "regular social listening, where we monitor social media trends and sentiment towards our brand on social media" and that it only examines publicly available social media data. "We never analyse individual customer social media accounts or use our customer service or other social media data in any way to analyse individual customer behaviours," added AIB.

Irish Independent