Giant scrap metal sculptures of Transformers have gone on show in Montenegro's capital Podgorica - the work of a young artist who saw a new role for his childhood heroes.

The towering figures, mostly made of old car parts and other waste, have been placed outside cafes, restaurants and on the city's main square.

The idea, art student Danilo Baletic explained, was to catch people's attention and send a message that waste can be used for the good of our planet.

"Autobots are here in a mission to prevent evil Decepticons - and the people who support them - from destroying our planet and its exhausted resources," the 22-year-old Mr Baletic said at the exhibition, which opened on Wednesday.

Mr Baletic said he made his first Transformer - named Rammtron - two years ago after visiting a scrap yard. Seeing piles of waste made the artist realise that people throw away plenty of useful materials, he explained.

"People all around the world should recognise that our waste can be recycled and transformed," he said.

So far, Baletic has installed seven Transformers in the centre of Podgorica, but he promised to make a new one for each of the planned visits to other countries in the region.

Residents have welcomed the newcomers in town. "Finally we see something new and different," said Selim Hasulovic.

Dozens of children have taken photos with the 45ft (14m) and 21-ton Megatron sculpture.

"I grew up this high because of you," said a metal-sounding voice from inside. "If you continue to pollute the planet, very soon there will be only me and the darkness here."