HSBC has been accused of unfairly targeting Syrians living in the UK after it was revealed the bank has written to a number of customers telling them it will close their accounts.

Manchester-based human rights group Rapar and the Syrian Rethink Rebuild Society, a not for profit organisation operating from the same city, said they have been working together to document cases in which Syrian nationals have been unfairly targeted by HSBC due to their nationality.

On its website Rapar said: "The Syrian community of Manchester has been subject to various accounts of profiling based on nationality, including police visits, airport stops, and the revoking of British nationality from dual nationals who travel to Syria. As a more recent development, financial institutions, most notably HSBC bank, have also been targeting their Syrian customers."

It said the two groups, itself and Rehink Rebuild Society, have "uncovered a pattern of abuse on behalf of HSBC in which the bank has turned down customers, inhibited or closed accounts, or refused mortgages for customers because their identity is Syrian."

One HSBC customer, Majid Maghout, a 26-year-old Syrian on a student visa, is quoted in the Independent as saying he was not contacted by HSBC but that when he tried to withdraw money his debit card was swallowed by the ATM.

"I contacted HSBC and they simply told me my account would be closed and I should have received a letter from them," he told the Independent. "HSBC told me it had nothing to do with me as customer – the issue was that I was a Syrian citizen.

"I'm a student. I have no money and I'm here thanks to a scholarship. I live on £400 a month and I've never transferred money to Syria. This is a case of discrimination. They could have checked my balance and my records, but they simply decided to close my account."

Rapar has published extracts of some of the letters it claims HSBC has sent out to its Syrian customers on its website. One of them reads: "Our records show that you are a resident in a country that is subject to financial sanction restrictions. Due to the increased requirements for compliance with international obligations concerning payments to and from sanctioned countries, we have taken the decision to close the above account(s).

"Please be assured that this decision is based on our own assessment of the risk and is not a reflection of you as a customer or the manner in which you have conducted you business with HSBC."

It is not the first time HSBC has been accused of prejudice against its customers. Last week it caused outrage among some in the Muslim community when three Muslim organisations, including the Finsbury Park mosque, were told by the bank that their accounts were being shut down.

The bank is likely to be taking a particularly cautious approach after it was fined a record £1.2bn in 2012 to settle allegations it allowed Mexican drug traffickers to move money around the financial system.

However, a spokesman for the bank said any decisions to close individual's accounts were "not based on race and religion" and that the closure of bank accounts held by Syrian nationals was in no way a "blanket approach".

"There are compliance issues to deal with regard to countries where there are financial sanctions and we want to have very high standards in this area," the spokesman said. "If you have links to those countries with sanctions then those links may be looked into. There are times when a review of an account is needed and that is done on an individual basis."

He said that he could not disclose the detail of what the bank would look at when reviewing an account and that the reasons for closure would often not be shared with the account holder. However, he did say that any movement of money between Syria and the UK via the account would potentially be one reason.

The Guardian has contacted a number of other UK banks including Santander, Lloyds and Barclays, to find out their approach to Syrian account holders but so far had no response.

A spokesman for the British Bankers' Association said: "Banks are understandably cautious about transferring funds to Syria and it is no surprise that they maintain strict internal compliance policies and have invested in sophisticated 'screening' software to help them spot potential sanctions as well as terrorist financing issues."

He added: "Many banks are operating an 'exceptions only policy' for transactions involving Syria – ie transactions will automatically be held for further scrutiny. As the situation deteriorates, transparency over arrangements with partners within Syria is reducing and satisfying due diligence will be increasingly challenging."