Scotland Yard is investigating claims that workers with the outsourcing firm Capita were paid by convicts to deliberately fit electronic ankle tags loosely, allowing them to slip the devices off when they wanted to go out.

Staff at the company, which runs the government’s Electronic Monitoring Service, were allegedly paid £400 a time to help at least 32 offenders beat their court-imposed curfews, according to a report in the Sun.

The Metropolitan police said the investigation was centred on the London borough of Newham. It said 14 people, including three current and former EMS workers, had been arrested in connection with “offences involving the monitoring of offenders”.

According to the Sun, the scheme was revealed after one offender was arrested on suspicion of attempted murder while he was supposed to be at home, under curfew.

Electronic tags, which are used to monitor conditions of a court or prison order, are usually securely attached to the ankles of defenders so they cannot be removed. They then send location data to a base unit in the offender’s home, ensuring they remain present during curfew hours. If they leave the area, the base unit sends an alert to a monitoring centre.

Police made their first arrest in the case on 3 January, when they held a 46-year-old former EMS employee in Romford, Essex, for conspiracy to pervert the course of justice and theft of tagging equipment.

He was taken to an east London police station and subsequently bailed to return to a police station on a date in early April.

Two current EMS workers – a 45-year-old man and a 57-year-old woman – were arrested on 18 January for conspiracy to pervert the course of justice. They were also bailed to return on a date in early April.

Eleven further people – none of them employees or former employees of the EMS – were arrested throughout January on suspicion of the same offence.

Capita was handed a £400m six-year contract for electronic tagging in July 2014. The company won the work after rival outsourced-security firms G4S and Serco were embroiled in overcharging allegations that led them to repay the government nearly £180m.