Hoax calls about fictitious fires or road traffic accidents, received at a rate of more than one every day, are costing Hertfordshire Fire and Rescue more than £340,000 a year.

The county's fire brigades made 173 wasted journeys, after receiving 556 fake calls during 2006/07, at a Government-estimated cost of £1,970 for each false alarm a crew responds to.

This means made-up emergencies cost the service £340,810 in the last financial year.

Herts Fire and Rescue, however, have radically improved their ability to detect hoaxers. In 2002/03, the service received 505 fake calls and crews were mobilised 436 times.

Penalties for misusing the 999 emergency system include a fine up to £5,000 or a six-month jail sentence.

Watford firefighter Derek Macleod said: "It can cost lives when people make those calls.

"Most people would say it makes them very angry. We get well supported by police and other agencies and if we find it's a hoax call, that's got any issues, we refer them to other people.

"There have been occasions where we're responding to a call and have to find out if it's a hoax call.

"Even if it's a hoax call, an abandoned call from a phone box from a child means we have to go and verify it. Sometimes you hear a call come through to a confirmed fire when you're responding to a hoax call. It's a terrible feeling and one that happens too often."

Control staff are able to identify hoax calls through a number of methods.

Abandoned Calls are recorded when no address is given and the caller hangs up during the call, and Challenged Calls are noted when no response is given after staff challenge the caller and establish the call is a deliberate false alarm.

Calls are also listed as deliberate false alarms when crews are sent to the scene and find no incident or emergency.

A Herts Fire and Rescue representative said: "We received 556 hoax calls during 2007, but only attended 173 of these as a result of rigorous call challenging carried out by our Control room personnel when they suspect the call is of malicious intent."