A Chinese interpreter who helped more than 100 learner drivers cheat on their theory tests has been sentenced to 12 months in prison.

Allyson Ng from Cardiff, Wales charged £110 to get Mandarin speakers through the written part of the UK driving test.

The 45-year-old is believed to have told candidates when to use "dui", Mandarin for "yes", on Highway Code questions.

Theory test officials became suspicious when they noted how many Chinese candidates hired her. Investigators listened to ­recordings of 27 of Ng's translations and found they were all fraudulent.

She was arrested at Cardiff theory test centre on 18 October 2012.

"This sentence sends a clear message that driving test fraud is a serious offence and will be dealt with accordingly," said Andy Rice, the Driving Standards Agency's head of fraud.

NG was jailed at Cardiff Crown Court after admitting 27 fraudulent translations and being found guilty of another 40 offences.

DSA chiefs are now in the process of tracing 94 people who used Ng to pass their theory test at a centre in the Welsh capital. The agency believes some candidates never bothered to learn the Highway Code because they knew Ng would get them through.

The drivers will face having their test pass certificates revoked and having to sit their whole driving test again.

In July, Mandarin ­translator Peter Hui, 55, of Birmingham, was jailed for a year after making up to £100,000 from also helping candidates cheat.

The £31 theory test is available in 21 languages but Mandarin is not one of them.

Under current legislation learners whose first language isn't English can use an interpreter on both the theory and practical driving tests.