Former British Steel owner Jingye Steel of China threatened consequences on Sunday following the nationalization of British Steel days earlier.

London must immediately stop using English law to "trample" on international investment rules, the company said, demanding full compensation for its investment losses.

Jingye took over the company - including its main plant in Scunthorpe, north-east England, and around 3,500 employees - when it was facing insolvency in early 2020. Heavy losses last year led to a decision to shut down the blast furnaces, prompting the government to take control of the firm.

Jingye said it had invested in the facilities and technology since the takeover, paid taxes and created "tens of thousands of jobs." The British government had committed an act of betrayal and forcibly seized its assets, the company said.

On Thursday, London justified its action by saying it was securing the future of steel production and skilled jobs. The nationalization had been in the works for some time.

Jingye said it intended to claim all investments made. The company said it had initiated a consultation procedure under the bilateral investment agreement and reserved the right to take legal action, including seeking international arbitration.

The Chinese government had also criticized the move in recent days.

China's Foreign Ministry said it would influence the way Chinese investors viewed the UK investment climate and public opinion on the trustworthiness of the British government.

The Ministry of Commerce lashed out at Britain for disregarding Jingye's contribution to the British economy. Beijing would continue to monitor developments and take measures to protect the interests of its companies, it said.