Over a dozen law firms have been held to ransom in recent weeks as attacks by cyber criminals increase.

In some cases hackers have demanded tens of thousands of euros not to delete all the files on the computer systems, which include private client information.

Solicitors are particularly vulnerable targets because of the large sums of money in their client accounts and huge volumes of data stored on the computer.

Cybercriminals hack into a computer system, often with an infected email, and encrypt all the files.

Money is then demanded for the key to unlock them. This type of attack is called Ransomware.

Security experts said attacks on the legal profession are increasing.

One IT security company alone has dealt with 14 law firms who have been targeted by cyber criminals over the past three months.

In all of these cases no ransom was paid and data was restored from backup systems.

Declan Branigan of eXpd8 IT services said it is becoming an epidemic which is not only affecting legal firms but all types of businesses.

He said this type of attack can cripple businesses and shut down computers for days preventing firms from operating.

He said while it is impossible to prevent these attacks there are measures that can be taken to reduce the risk including having up to date anti-virus software, web filters and a firewall.

Mr Branigan said if a company is attacked the computer system should be shut down immediately.

Most of these attacks go unreported for fear of losing client confidence.

One solicitor who spoke to RTÉ news, and wished not to be named, said it was potentially disastrous for his firm.

He said he panicked when he realised the seriousness of the attack and that the client account system was in jeopardy.

He continued "we would be accountable for a closing balance of €4-5m every day to clients and trying to identify 2,500 clients, whose money was actually in the account to the cent, was never going to be achievable going forward".

He did not pay a ransom and the financial client accounts were restored from a back-up system. However, he did lose some data.

The Irish Law Society has issued a warning to its members to be vigilant and take precautions.

Its President Ken Murphy said it is important that solicitors have security measures in place and back up their data.