A "significant amount" of private data including criminal records has been hacked from the Legal Aid online system, the Ministry of Justice (MoJ) has said.

The MoJ said said it became aware of a cyber-attack on the Legal Aid Agency's online digital services on April 23 of data dating back to 2010. It then became aware the incident was "more extensive than originally understood".

Legal Aid Agency chief executive Jane Harbottle apologised for the breach, saying she understood the news "will be shocking and upsetting for people".

The group that carried out the attack claimed it accessed 2.1 million pieces of data, according to the PA news agency. The MoJ has not verified that figure, however.

The ministry urged members of the public who have applied for legal aid in this time period to take steps to safeguard themselves.

"This data may have included contact details and addresses of applicants, their dates of birth, national ID numbers, criminal history, employment status and financial data such as contribution amounts, debts and payments," it said.

It also warned the public to be alert for any suspicious activity, including unknown messages or phone calls, and to update any potentially exposed passwords.

"If you are in doubt about anyone you are communicating with online or over the phone you should verify their identity independently before providing any information to them," it said.

The ministry said it was working with the National Crime Agency and the National Cyber Security Centre, and has informed the Information Commissioner.

The Legal Aid Agency's online digital services, which are used by legal aid providers to log their work and get paid by the government, have been taken offline.