Police are investigating a 21-year-old “fake paramedic” who is believed to have had contact with more than 100 patients.

The Metropolitan Police said it was contacted in July with concerns about the actions of a London Ambulance Service (LAS) member of staff which included responding to 999 calls and discharging patients at the scene, the Evening Standard reported.

Following inquiries, a man was arrested at an address in Hornchurch, Essex, on September 27, in relation to a period between May and July this year.

In a statement, police said: “The 21-year-old was arrested on suspicion of fraud, burglary, theft by employee, assault by beating, dangerous driving, driving otherwise in accordance of licence, and driving without insurance.”

According to the Evening Standard, the man may have treated more than 100 patients.

The LAS confirmed on Friday that it “immediately ended” the man’s employment.

“We take our responsibilities to patients extremely seriously. As soon as we became aware of the activities of this individual, we initiated a full internal investigation, informed the police and contacted patients affected,” it said in a statement.

“Following our investigation, we have improved, and will continue to improve, our security, systems and processes.”

The service said it would continue to “work closely” with commissioners, NHS Improvement and the Care Quality Commission (CQC).

It added: “Changes designed to eliminate the possibility of anyone with internal knowledge of our computerised systems being able to misuse them in this way, have already been implemented.”

The police said the man was taken into custody at a south London police station and later released under investigation. Inquiries are said to be ongoing.

A spokesman for the CQC said: “I can confirm that CQC is aware of this matter. As a result CQC carried out a two day unannounced focused inspection at the London Ambulance Service NHS Trust on 20 and 21 November 2018.

The findings will be published “in due course”.