US Secretary of State Mike Pompeo issued the warning as he highlighted growing concerns about Rome’s economic relationship with Beijing. Italy raised hackles in Washington last year when it became the first major Western economy to join China’s international infrastructure project, the Belt and Road Initiative. The tie-up has yet to yield any significant economic gain but Mr Pompeo accused Beijing of trying to muscle in to satisfy its own strategic ambitions.

He said: “The foreign minister and I had a long conversation about the United States’ concerns at the Chinese Communist Party trying to leverage its economic presence in Italy to serve its own strategic purposes.

“The United States also urges the Italian government to consider carefully the risks to its national security and the privacy of its citizens presented by technology companies with ties to the Chinese Community Party.”

Italian Foreign Minister Luigi Di Maio said ministers were aware of US concerns over Chinese 5G technology, and “fully realise the responsibility faced by every country when dealing with security”.

US attention has focused mainly on Huawei Technologies, the world’s biggest telecoms equipment maker.

Washington has told its European allies the Chinese firm poses a security threat, noting that Chinese companies and citizens must by law aid the state in intelligence gathering.

US allies, such as Britain, have announced bans on Huawei equipment in future telecoms infrastructure but Italy has so far declined to do so.

However, the company was recently excluded from one major tender and a senior government official said the state was ready to impose tougher rules in deals involving the Chinese firm.

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Mr Di Maio said Italy was looking for the European Union to adopt a common position on 5G development.

Huawei has denied it poses a risk and the head of its Italian operation, Luigi De Vecchis, insisted it was ready for any scrutiny to show that its technology was safe.

Mr De Vecchis said: “We will open our insides, we are available to be vivisected to respond to all of this political pressure.”

Mr Pompeo’s trip to Italy was scheduled to include meetings in the Vatican but officials announced they had rejected the Secretary of State’s request for an audience with Pope Francis and accused him of trying to drag the Catholic Church into the US presidential election by denouncing its relations with China.

The extraordinary remarks from the two top diplomatic officials at the Vatican came after Mr Pompeo accused the Church of putting its “moral authority” at risk by renewing an agreement with China over the appointment of bishops.

Vatican Secretary of State Cardinal Pietro Parolin and Foreign Minister Archbishop Paul Gallagher, said Francis had declined Mr Pompeo’s request as he avoids meeting politicians ahead of elections.

Cardinal Parolin said: “The Pope had already said clearly that political figures are not received in election periods.”

President Donald Trump has campaigned on his hard line towards China ahead of the November 3 election.