The animal welfare group Animal Concern has condemned Aberdeen City Council's plans to cull deer on Tullos Hill in the city as "utter madness".

John F Robins, Animal Concern's campaigns co-ordinator, said plans for a deer cull to protect new trees to be planted as part of its Tree for Every Citizen project were unworkable and unjustified.

Animal Concern is one of eight organisations including Aberdeen Animal Rights, Peta and the Scottish Tree Trust which have signed a letter opposing the plans. The groups argue the scheme is "unethical and unjustifiable".

The council's plans have put it in opposition to animal welfare groups over the past 12 months. Director of housing and environment Pete Leonard has said the Tree for Every Citizen project "will not only revitalise the landscape of Tullos Hill but also help promote its wildlife and archaeological significance".

However, the animal welfare groups believe the area does not need to be changed. In their letter they said: "It is already a haven for a diverse ecosystem of flora and fauna and it could be embellished and enhanced without killing the resident deer and destroying what is already their natural habitat."

Mr Robins said he didn't believe the council's plans were workable as previous attempts to plant trees in the area had failed. "It's utter madness. The council will not listen to anybody."

He added that if deer are killed, more deer will simply move in. "Locals are preparing to have direct action against the guns. We are urging everybody to be very cautious. We are talking about guns, scrublands and protesters – and the three don't go together."

Suzanne Kelly, who is planning to run for a council seat in the May elections, does not believe the topsoil on the hill can support mature trees. "There's an awful amount of industrial waste, even though the city says this part of the hill was never used as a dump."