Police hope the net is closing on the feathered suspects accused of 'soiling the stairs' of their Norwich headquarters.

The offenders are described as feral, known by the name of Columba livia and roosting in a balcony hideout behind air-conditioning units.

They have been charged with causing a 'health and safety welfare issue to staff' at the Bethel Street police station – and now Norfolk police has submitted plans to rid their HQ of pigeons.

The proposal, estimated to cost �1,395, includes using netting to cover a balcony to stop 'pigeons soiling the stairs and walkway area', which is also a main fire escape.

Norfolk police's Marcel Pfrang stated in planning documents: 'At the rear of this building between the 1930s and 1960s sections there is a stairwell and walkway constantly being soiled by pigeons perching on the balcony above.'

Mr Pfrang said the netting would stop this and 'provide better hygienic conditions to police officers'.

It is also suggested a full clean to remove mess on the ground floor and balcony area will take place if the proposal is approved by the city council. A pest control expert notes the diseases from which staff are at risk include extrinsic allergic alveolitis, also known as 'pigeon fancier's lung'.

Simon Collins, area operations manager of NBC Bird and Pest Solutions, wrote to planners: 'Removing and cleaning up guano, bird droppings, faeces, whatever you call it, is a job that needs to be done and carried out by a professional.

'Guano is unsightly, unsanitary and poses a health and safety risk, and it doesn't stop there as it is often infested with blood-festing insects and its acidic matter causes damage to the fabric of buildings which, in turn, leads to higher cleaning and repair bills.

'The amount of potential birds and fouling should be considered a serious health hazard and treated as a matter of urgency.'

The police station is part of City Hall, which already has a post and wire system to deter pigeons, which makes it difficult for birds to perch. A gel substance has also been piloted by the city council, which tricks pigeons into believing ledges are on fire. The 1930s building is not on fire – and no pigeons are harmed by the gel.