The Health & Safety Executive (HSE) is warning parents to explain to their children the dangers of playing on construction sites, after one child died and 25 were injured on construction sites in 2008/09.
Dozens more children are seriously injured on sites every year, according to the HSE.
As the school summer holidays get underway, the HSE wants to remind children and parents that construction sites are not adventure playgrounds.
Construction companies are being reminded that sites should be secure, with good fencing to prevent public access and with regular checks carried out.
Philip White, HSE's chief inspector of construction, said: "Without proper precautions, construction sites are dangerous places for those who work on them day in day out, never mind the risks to children who simply see them as exciting playgrounds and don't understand the dangers.
"Of course we want children to make the most of their summer holidays by enjoying the outdoors, but building sites are not the place to do it. We need parents to help this message hit home.
"Construction managers should check their sites are secure, and in areas where children live and play they should ensure that risks to children are properly controlled."