China has criticized the nationalization of British Steel, saying it “firmly opposes and is strongly dissatisfied with the British government’s decision.”

On Thursday, the UK government said taking the loss-making business into public hands would protect jobs and safeguard a “vital national capability”.

The UK took control of British Steel’s Scunthorpe operations last year, although it was still owned by China’s Jingye Group, limiting the government’s ability to direct its future.

China’s Ministry of Commerce said on Friday that the measures “seriously infringed on Jingye’s legitimate rights and interests and seriously undermined the trust of Chinese companies investing in the United Kingdom.”

He also called on Britain to “faithfully fulfill” its obligations under the China-UK Bilateral Investment Treaty.

“Disregarding Jingye’s important contribution to the UK economy and society, the British side forcibly took control of the company in the name of national security,” the ministry said.

The statement added that Beijing would closely monitor developments and support Chinese companies to protect their rights, but did not specify what protecting the rights of Chinese companies might entail.

The decision to nationalize British Steel threatens to strain the relationship between London and Beijing just as Andy Burnham becomes prime minister on Monday.

The incoming prime minister will have to weigh his approach to the issue against the economic benefits of ties to the world’s second-largest economy.

The China-UK Bilateral Investment Treaty is a legally binding agreement that was signed in 1986. It was designed to promote and protect investments between the two countries.