A £500,000 public art project has been unveiled in Burnley - but the 19 creations are invisible to the human eye.

The artwork across the town can only be seen when shown under UV lights, which will be switched on by motion sensors or by timers.

The innovative pieces -entitled Invisible - have been commissioned' by 15 youngsters from four schools as part of The Big Art Project, a public art initiative set up by Channel 4 and supported by Arts Council England and the Art Fund.

Burnley is the first of seven sites across the country to have its work go on display, following a two-year pro-cess involving community focus groups.

The town is the only site to have a commissioning group of teenagers, who selected London-based arts collective Greyworld to work with.

The pieces, which can be found on sites including the Old Cinema on Cow Lane, Charter Walk Shopping Centre, the bus station and an underground car park, are painted using UV-sensitive materials.

They largely focus on the subject of local heroes' and include portraits of teachers, charity workers and Burnley FC's mascot Bertie Bee, as well as fun pictures of vending machines, movie posters and street signs.

The creation process will be shown on a Channel 4 doc-umentary in November.

Artist Andrew Shoben, of Greyworld, said: "People will be able to discover these pieces and it will really make them think twice about public art."

Mike Smith, executive producer for The Big Art Project, said: "Burnley was picked because of the potential to discover what art could do in a place like this."

Council leader Gordon Birtwistle added: "Over two years our youngsters have achieved something unique, something to make the cou-ntry sit up and take notice."