Concern is mounting that the Ministry of Justice's central contract for interpreting work could prove a false economy, incurring knock-on costs for criminal justice agencies.

A week into the new framework agreement under which courts and justice agencies across England and Wales obtain interpreters and translators through a single agency, questions have already been raised about the quality of the service.

Applied Language Solutions, set up by Gavin Wheeldon in 2003 and acquired by Capita in December 2011, won the contract last August following a tender process. Criminal justice agencies had previously contacted interpreters directly from a national register.

The MoJ expects the new service to save £18m a year, cutting translating costs by nearly a third.

ALS has provided interpreting services for some police stations since 2009. The Gazette has in the past reported concerns raised by defence solicitors over the quality of service.

Magistrate Richard Bristow, chair of the West London bench, told the Gazette that since 1 February he has had ‘lots of problems’ with the new system, with either two ALS interpreters attending hearings or none at all. He said colleagues had reported a fall in the quality of interpreters. Bristow warned that the new regime could turn out to be a ‘false economy’.

He said: ‘If cases have to be put off, the cost to the police, the Crown Prosecution Service and the courts is huge. There are bound to be appeals from people who say they did not get a fair trial due to inadequate interpretation.’

The Professional Interpreters’ Alliance (PIA), which represents public service interpreters, has also voiced concern. PIA director Madeleine Lee told the Gazette that 60% of the 2,300 interpreters on the national register have refused to work for ALS because of its pay policy and allegedly low standard of qualification required.

Since the start of February PIA members have gone to courts to observe. Lee said: ‘We are already hearing horror stories from all over the country. Being a court interpreter is a specialised and difficult job. You have to be accurate as people’s liberty is at stake.’

An ALS spokeswoman said all ALS interpreters hold recognised qualifications and undergo independent assessment. She said more than 3,000 interpreters have registered to work with ALS and are being vetted to ensure they have the necessary qualifications and experience.

She said ALS had not been made aware of complaints of the wrong interpreter being sent, but acknowledged that there have been circumstances where it had not been possible to fulfil a booking at short notice.

She added: ‘Prior to rollout there was limited accurate management information available regarding the expected daily volumes of short notice interpreter requests.

‘One week into rollout we now have a much clearer picture of daily volumes, which is enabling us to implement more resource with a focus on those languages where we are experiencing higher demands.’

An MoJ spokesman said it is ‘closely monitoring’ the operation of the new contract.