It is nothing less than annoying if pigeon droppings land in the garden. It is all the more serious when the droppings are contaminated with radioactivity.

The environment campaigners Greenpeace are calling for an end to all nuclear reprocessing at the Sellafield nuclear plant in Cumbria following the publication of an official report yesterday. It discovered that wild pigeons roosting at the site and contaminated with radioactivity had carried it to a garden two miles away in Seascale.

The pigeons, described by Greenpeace as "flying nuclear waste", were contaminated after roosting in old buildings at Sellafield. They began feeding in the garden over a two-year period and the soil was contaminated to such an extent that the garden was dug up by British Nuclear Fuels Ltd (BNFL) and sent to a nuclear dump along with a number of garden gnomes. The pigeons were destroyed last year. The report, published by the Committee on Medical Aspects of Radiation in the Environment (Comare) and the Radioactive Waste Management Advisory Committee (RWMAC), acknowledged that the contamination of the garden was not significant.

The radioactive dose received by the residents was about half the annual limit for members of the public while the doses received by neighbours in adjacent properties were "not of any radiological concern", according to the report.

But the report recommends that further research into possible contamination at nuclear sites, including the risk posed to other wildlife such as insects and other birds should be carried out. It also reported that authorised discharges of radioactive gases from Sellafield's chimneys might have caused some of the radiation contamination.

Prof Bryn Bridges, chairman of Comare, said it was possible the doses could have been higher. He described the contamination as a "worrying discovery".

BNFL apologised for the contamination and said it was pleased the report acknowledged the steps it had taken to remedy the situation. It also accepted the report's criticism that mismanagement was at the heart of the problem.

In a statement yesterday, BNFL said it had committed considerable resources to resolve the issue: "This involved culling the birds, controlling the birds' feeding, restricting access to these older buildings and completing a site habitat control programme. A programme of remediation was also carried out in Seascale, after discussion with the property owners and the regulator."

Greenpeace described decisionmaking at Sellafield as "hopelessly inadequate" and said the problem did not die when BNFL culled the birds. Dr Helen Wallace of Greenpeace said: "Nuclear waste could still be spreading through wildlife into people's homes and gardens. Today's reports warn that other wildlife, such as insects and doves, may also be involved in the spread of nuclear waste from nuclear sites into people's homes and gardens."

BNFL should be made to properly contain and monitor all existing waste, she added.