China poses the greatest threat to Britain and world security this century, said the candidate for prime minister, the former head of the British Treasury Rishi Sunak.

Sunak and Foreign Secretary Liz Truss are vying for the leadership of the Conservative Party to replace Boris Johnson, Reuters reports.

Truss is leading the polls among members of the Conservative Party who will choose their new leader and next UK prime minister, but Sunak is hoping weeks of fuss and debate will help his campaign ahead of the election results due on September 5.

China poses the biggest long-term threat to the UK, global economic and national security, Sunak said in a statement.

He said he would ban the Chinese government-funded Confucius Institutes in the UK and use intelligence agencies to help British businesses counter Chinese espionage. He said he would also consider a case to ban Chinese acquisitions of key British assets, including strategically important technology companies.

Truss, a spokesman for the campaign, said the Foreign Secretary strengthened Britain's position on China and helped lead the international response to increased Chinese aggression.