DOG walkers are being urged to be extra vigilant to stop their pets attacking sheep and newborn lambs.
Farmers in the South Downs have put out the warning.
They say as the weather starts to warm up more people take advantage of the national park to exercise their pets.
A minority of walkers still allow their dogs to roam off their leads when around sheep.
John Archer, environment and land use adviser for the NFU South East, said: ‘Every year a number of sheep and lambs across the national park are killed or injured by out-of-control dogs.
‘These attacks cause unnecessary suffering to the animals and are very distressing for farmers.
‘We’ve already seen attacks by dogs on sheep over the past few months, with sheep being killed or injured and ewes going on to lose their lambs.
‘We know that many attacks and losses go unreported.’