The British government on Tuesday scrapped a huge contract to clean up Britain's Sellafield nuclear plant after the company in charge was accused of delays and exceeding budgets.

Nuclear Management Partners (NMP) -- comprising companies from Britain, France and the United States -- had won the 9.0-billion pounds ($13.6-billion, 11-billion-euro) contract in 2008 to decommission facilities at the site in Cumbria, north west England.

The government's Nuclear Decommissioning Authority (NDA) will now take ownership of the clean-up.

Energy and Climate Change Secretary Ed Davey described Sellafield as "the biggest and most complex nuclear site in Europe" and said "it's right that we keep the way it's being managed under constant review".

He added that a "strategic partner" would be found from the private sector.

NMP, which comprises US engineering group URS, British firm AMEC and French energy firm AREVA and employs 10,000 workers on site, was granted a five-year extension in 2013 but came under criticism for its performance.

The Public Accounts Committee and the National Audit Office both highlighted cost overruns and hold-ups.

Following a year-long review, the NDA concluded that "simplifying" its relationship with Sellafield would bring "greater clarity and focus".

"This decision is the result of careful consideration and review of various commercial approaches in use where the combination of public and private sector comes together to deliver complex programmes and taxpayer value," said NDA chief executive John Clarke.

Industrial union GMB welcomed the contract termination.

"We believe NDA wanted to terminate the contract in 2013 following a report it commissioned, but was overruled by ministers," said Gary Smith, national officer of the GMB.

"Over 2.0 billion pounds has been spent with NMP since they extended the contract. Who is going to be held to account for extending the contract? GMB members, the community and taxpayers need to know."

French firm Areva, which has a 20 percent stake in NMP, said that it "respected" the government's decision but that it hoped to be part of its future plans.

"We want to continue to provide our expertise and support," Areva said in a statement issued to AFP, adding it was "committed to the British nuclear industry and the NDA."

Shadow energy minister Tom Greatrex accused the Conservative-led government of "ignoring warnings over failing project delivery and escalating costs".

However, NMP general manager Iain Irving said since the contract was extended "the site has enjoyed one of its best ever periods of performance and progress".

"Importantly, over the last two years, we have consecutively achieved the site's best overall safety records," he added.