A catalogue of serious safety “failings” at Sellafield have been alleged in a BBC documentary.

An investigation by Panorama, including information from a whistle-blower and thousands of leaked documents, uncovered “poor management, run-down infrastructure and safety failings” at the nuclear site at which 10,000 workers are based.

Specific allegations from reporter Richard Bilton centred on staffing levels running below minimum safety levels in some areas and a number of storage facilities that are said to be in poor condition.

Mr Bilton reported: “Years of neglect have left parts of the site run down and vulnerable and there are not always enough workers to meet safety levels.

“If you expected safety that was beyond reproach then you’d be wrong.”

Sellafield’s head of nuclear safety Rex Strong rejected Mr Bilton’s claim that operating below minimum staffing levels is dangerous.

The firm added that safety and security are its “overriding priority” and points to its current safety record as the best in the site’s history.

Other “failings” alleged by the documentary included safety alarms being ignored and dangerous liquid plutonium and uranium being stored in unsuitable containers; both claims were rejected by Sellafield.

The whistleblower – a former high-level site worker – added that he was “worried every day” about a potential incident.

The rising clean-up cost of the site – said to be around £162 billion – was also highlighted, leading to MP Meg Hillier, who chairs the Public Accounts Committee, to call for “more transparency on cost”.

She added: “It feels like a blank cheque.”

Additionally, a number of managers at Nuclear Management Partners, the consortium which ran the site until April, expressed concern at the condition in which they found some of Sellafield’s facilities when they took over the running of the plant.

David Pethick, director at NMP, said some of the infrastructure was “poor” and there were “facilities or equipment on the verge of breaking down”.

John Clarke, chief executive of the site’s owners Nuclear Decommissioning Authority, responded: “There is no way myself and the 10,000 people who work here would live on the doorstep if we thought we were putting ourselves or our community at risk.

“It remains absolutely safe today, tomorrow and in the future.”

The Office for Nuclear Regulations added that there have been “significant improvements” in safety standards on site.