Regular visitors to Penryn's Glasney Valley have seen a recent increase in fly tipping and other anti-social acts, with local volunteers now asking for help from police.

The Glasney Greenspace Regeneration Project (GGSRP), a group which has spent the last few years cleaning up the valley and campaigning for improvements to its facilities, has reported the dumping of rubbish such as a bike, waste from a newly installed council bin which had been ripped from its post, a laptop computer, and several mopeds, which had been left to leak fuel into the river.

The group said that although the town council and police had been contacted, the mopeds would find their way back into the river, and it ended up falling to the GGSRP and members of the public to keep removing them, with the final removal organised by a neighbour.

As well as despoiling the river and surrounding walkways, vandals have smashed a bug hotel made by local children on May Day and put in place for the Arts Festival, which has since been repaired by the group, and rolled a concrete seat, described as "barely moveable by two strong men" down one of the valley's banks.

Pip Carlton-Barnes, from the GGSRP, said: "The bike was thrown into the river by a group of young people, aged around 10 to 12, not more than 10 feet away from Pete [a volunteer] as he was in the river clearing.

"Phil [another volunteer] politely asked why they had done it and who the bike belonged to but no response was made. The bike has since been returned after a relative saw the bike on our facebook page."

She also described ripping down the new waste bin as "absurd" as it was "one thing local people have consistently asked for."

The group has now asked Falmouth police if a PCSO could include the valley in their beat, and said that although the council are sympathetic, with limited resources and funds and a decrease in police presence there is not much that can be done.

She added that people on the whole: "Are supportive of what we are doing and go some way to help. Many of the young people we talk to appreciate keeping the valley tidy makes it better for their enjoyment."