The White House has stepped up warnings to the UK about allowing Huawei into its 5G telecommunications networks, saying that any such move would pose a risk to MI5 and MI6, the British secret intelligence services.

Robert O'Brien, the US national security adviser, told the Financial Times that any UK government decision to allow the Chinese telecoms company to participate in the country's ultrafast 5G networks risked giving the Chinese Communist party access to the "most intimate" details of British citizens and the ability to steal national secrets.

"They are just going to steal wholesale state secrets, whether they are the UK's nuclear secrets or secrets from MI6 or MI5," Mr O'Brien said in an interview. "It is somewhat shocking to us that folks in the UK would look at Huawei as some sort of a commercial decision. 5G is a national security decision."

Washington has repeatedly urged the UK to completely ban Huawei, but the warning from Mr O'Brien raises that pressure to a new level. It comes as Prime Minister Boris Johnson prepares to decide whether to ban Huawei from the country's 5G networks.

British security officials last year concluded that any risk from Huawei can be mitigated if it is barred from the network "core", but US officials disagree with that assessment.

Australia has also urged the UK to exclude Huawei from its 5G networks.

One reason Britain faces such pressure is because it is one of the "Five Eyes" partners — with the US, Canada, Australia and New Zealand — that share critical intelligence. The US has previously said allowing Huawei in 5G networks could limit intelligence sharing.

Robert O'Brien, US national security advisor. Photo / Getty Images

In a stark warning about the threat to individuals' data, Mr O'Brien said China would be able to "micro-target" individuals to "exploit their hopes and their fears" by gaining access to personal details. US concerns about 5G had been amplified by what he said were growing Chinese efforts to obtain the genetic data of people around the world.

US security agencies have in recent years boosted their focus on Chinese investment in US biotech companies and the hacking of patient data from hospitals and laboratories.

"If you get all the information on a person and then you get their genome, and you marry those two things up, and you have an authoritarian state wielding that information, that is an incredible amount of power," Mr O'Brien said. "Why the UK would sign up for such a programme is astonishing."

Robert O'Brien on . . .

The decision facing Boris Johnson

"It is somewhat shocking to us that folks in the UK would look at Huawei as some sort of a commercial decision. 5G is a national security decision."

Risks to personal data

"If you get all the information on a person and then you get their genome, and you marry those two things up, and you have an authoritarian state wielding that information, that is an incredible amount of power."

Angela Merkel's dilemma

"While the German elites may have been happy to do a deal with China or Huawei, German citizens are starting to revolt."

Silence on the plight of the Uighurs

"There are too many governments, European governments and others, which are more concerned about offending China and potentially losing out on some economic gain from their relationships with China than standing up for their principles."

The pressure on the UK is part of a stepped-up campaign to ensure as few countries as possible let Huawei into their 5G networks. The White House this week created a new role to co-ordinate 5G policy, which will be filled by Robert Blair, a West Wing official.

President Donald Trump this month lobbied Mr Johnson during a visit to London on the issue of Huawei. US officials have in the past suggested that a decision not to ban Huawei could impact the US-UK trade deal that Britain wants to conclude after Brexit.

In his interview with the FT, Mr O'Brien also fired a shot across the bow of German Chancellor Angela Merkel as Berlin debates how to handle Huawei. He was speaking after Matt Pottinger, his deputy, returned from talks with top German officials.

Ms Merkel does not want to ban Huawei because of the fear of economic retaliation but she has come under pressure from lawmakers in her party, the Christian Democrats, who have been working on a draft law that would raise significant hurdles to Huawei.

"While the German elites may have been happy to do a deal with China or Huawei, German citizens are starting to revolt . . . You are even seeing that within Chancellor Merkel's party," he said. "German citizens just are not ready to sign up for their state to become a vassal of Beijing, and the first step on that path is allowing Chinese 5G into Germany."

Mr O'Brien added that European citizens and people in allied countries, such as Japan, Australia and New Zealand, were "starting to understand that letting Huawei into their countries is like letting the Trojan horse into Troy".

Huawei has denied that it helps the Chinese government spy. But the US and some allies are concerned that the company could either actively engage in espionage or would be unable under Chinese law to refuse requests from Beijing to hand over any data on its servers involving non-Chinese nationals. Some countries are trying to balance the national security concerns with the lower cost of Huawei equipment.

The US national security adviser also hit out at countries that prioritise economic interests with China over criticising Beijing on its human rights record, particularly in Xinjiang where the Communist party is detaining 1m Uighurs in re-education camps.

"What has been surprising is governments . . . including governments that pride themselves on their promotion of human rights, have been less than forthright," he said. "There are too many governments, European governments and others, which are more concerned about offending China and potentially losing out on some economic gain from their relationships with China than standing up for their principles."

He said it was "shocking" that many Muslim nations in addition to the Organisation of Islamic Co-operation — which includes US allies such as the UAE, Turkey and Saudi Arabia — had not voiced support for the Muslim Uighurs. He said the reluctance was directly due to China using debt diplomacy and financial muscle to muzzle criticism.

"They have gained incredible leverage over countries where they literally control them because of the loans China has made," Mr O'Brien said.