The British government privately told the Chinese technology giant Huawei that it was being banned from Britain’s 5G telecoms network partly for “geopolitical” reasons following huge pressure from President Donald Trump, the Observer has learned.

In the days leading up to the controversial announcement on Tuesday last week, intensive discussions were held and confidential communications exchanged between the government and Whitehall officials on one side and Huawei executives on the other.

As part of the high-level behind-the-scenes contacts, Huawei was told that geopolitics had played a part, and was given the impression that it was possible the decision could be revisited in future, perhaps if Trump failed to win a second term and the anti-China stance in Washington eased.

Senior Huawei executives have gone public since Tuesday’s decision saying that they hope the British government will rethink, apparently encouraged by the results of back-channel contacts.

The government’s private admissions are out of kilter with public statements last week by ministers, who said Huawei had been banned because of new security concerns raised by the National Cyber Security Centre (NCSC), which is part of GCHQ.

In the Commons, Oliver Dowden, the secretary of state for digital, culture, media and sport, said new sanctions forbidding the sale of US-produced components to Huawei – meaning the Chinese company will have to source them from elsewhere – had changed the balance of security risk.

“The new US measures restrict Huawei’s ability to produce important products using US technology or software,” he said. “The National Cyber Security Centre has reviewed the consequences of the US’s actions …

“The NCSC has now reported to ministers that they have significantly changed their security assessment of Huawei’s presence in the UK 5G network. Given the uncertainty this creates around Huawei’s supply chain, the UK can no longer be confident it will be able to guarantee the security of future Huawei 5G equipment affected by the change in the US foreign direct product rules.”

Last week’s move reversed a decision made in January when the government announced that Huawei equipment could be used in its new 5G network on a restricted basis. This led to fierce criticism from Tory MPs, including former party leader Iain Duncan Smith, who described Huawei as an arm of the Chinese Communist party and a risk to the UK.

Tuesday’s reversal of that announcement pleased all but the most hardline anti-Huawei Tory MPs. But it has called into question Boris Johnson’s manifesto promise to supply superfast broadband to every home and business across the country by 2025, and led the Chinese to warn of retaliation. However, Beijing’s response was more muted than many on the UK side had feared.

The decision has also led to accusations that the UK government is putting its loyalty to Trump – who is waging a diplomatic war against China over coronavirus, human rights, trade, its stance on Hong Kong, and Huawei in the run-up to the US presidential elections – before its commitment to put the UK in the vanguard of global technological advances.

In a press conference at the White House on Tuesday, Trump immediately claimed credit for the UK decision – “I did this myself, for the most part” – and said he was trying to force other nations not to use Huawei.

Rejecting claims that the UK government was kowtowing to Trump because of the UK’s need to sign a post-Brexit trade deal with Washington, Matt Hancock, the health secretary, dismissed the president’s claim. “We all know Donald Trump, don’t we,” he told Sky News. “But I think this is a sensible decision. All sorts of people can try to claim credit for the decision but this was based on a technical assessment by the National Cyber Security Centre about how we can have the highest quality 5G systems in the future.”

Lord O’Neill, the economist who was brought into the government as commercial secretary to the Treasury in 2015, said the private explanations given to Huawei made the decision seem “more rational”.

He said: “Given that the prime minister continues to describe himself as a Sinophile, one would think that he is trying to minimise the damage. Otherwise, the decision does not make any sense whatsoever. China has been the biggest contributor to global GDP in the last 20 years. So why would we want to cut ourselves off from that?”

However, Tory MPs will be infuriated by any suggestion that there could be another U-turn on Huawei. Several have vowed to push Johnson further to ban Huawei from the UK altogether, including from existing 2G, 3G and 4G networks.

The Labour MP Kevan Jones, a former defence minister who now serves on the Commons intelligence and security committee, said it was clear US pressure had swayed the government. “Of course security should be the number one priority, but it is clear this decision was taken for geopolitical reasons rather than taking into account the economic costs to the UK,” he said.

This week the US secretary of state, Mike Pompeo, will visit London and hold talks with Tory MPs, including Duncan Smith, who are opposed to Huawei. He is expected to try lobby other European governments on his visit.

Huawei refused to comment on its talks with civil servants and ministers and pointed to a statement issued last week saying: “This disappointing decision is bad news for anyone in the UK with a mobile phone. It threatens to move Britain into the digital slow lane, push up bills and deepen the digital divide. Instead of ‘levelling up’ the government is levelling down and we urge them to reconsider. We remain confident that the new US restrictions would not have affected the resilience or security of the products we supply to the UK.”

A DCMS spokesperson said: “We have banned the purchase of any new 5G Huawei equipment after 31 December this year, and will remove all Huawei equipment from 5G networks by the end of 2027.

“This was a decision taken by ministers at the National Security Council, based on technical, security analysis from the world-leading National Cyber Security Centre.”