More than a fifth of alleged rapes reported in Hertfordshire are not pursued by police, new figures have revealed.

According to a report published by Her Majesty’s Inspectorate of Constabulary last week, 21% of Hertfordshire rape complaints in the year to March 2013 were later classed as ‘no crime’.

The proportion of discontinued cases was the third highest in England and Wales, and far higher than the national average of 12%.

According to the report, 110 adults and 63 children told Hertfordshire police they had been raped in the 12-month period, just over half the national average rate per head.

Although its ‘no crime’ rate is high, Hertfordshire Constabulary’s detection rates of 21% for adults and 37% for children are better than the national averages of 18% and 31%.

Since 2010, when a report by Her Majesty’s Crown Prosecution Service Inspectorate highlighted the issue, the national ‘no crime’ rate has fallen from 16% to 12%, but in Hertfordshire it has risen by 13% in the same period after an 8% figure was previously record.

A spokesman from Herts Rape Crisis and Sexual Abuse Centre said: “It sends out a message to women and girls that have been assaulted that you won’t get past the first hurdle because police don’t believe you.”

A police spokesman pointed to the higher-than-average detection rates, and said: “We have worked hard to both focus on reduction of crime while at the same time encouraging victims of such crimes to report them.

“We need to reassure victims to come forward, as we will conduct a full and thorough investigation.”

She added that Herts police was one of the first forces to set up a unit specifically dedicated to investigating rape and sexual assault.