LONDON (BLOOMBERG) - UK Prime Minister Boris Johnson will put his friendship with President Trump to the test this week as he announces whether to allow Huawei Technologies a role in the country's fifth-generation wireless broadband networks.

In the week that the UK ends its 45-year relationship with the European Union, Johnson is expected to make a series of critical infrastructure decisions that could shape his premiership - and the country - for years to come.

The premier is poised to allow Huawei to take a role in developing 5G, despite calls from Trump to ban the Chinese firm over concerns that it could make the network vulnerable to spying in the future. Huawei has always denied posing a security risk. An announcement could come as early as Tuesday (Jan 28).

The Huawei decision is perilous for Johnson. If he bans the company, he risks failing to equip the UK with the technology Huawei is well placed to provide and betraying his pledge to voters to spread ultra-fast internet services across the country.

If he allows Huawei to go ahead, he faces the potential loss of US intelligence cooperation and an angry backlash from the White House at a time when he's seeking a trade deal with Britain's closest ally.

Trump and Johnson discussed Huawei on Friday in a phone call following weeks of lobbying from the US to try to persuade the UK to ban the Chinese company from 5G networks over security concerns.

Secretary of State Michael Pompeo added his voice to the public warnings from US officials, ahead of a trip to Britain this week.

"The UK has a momentous decision ahead on 5G," he said on Twitter. Pompeo endorsed the view of British Conservative lawmaker Tom Tugendhat that "only nations able to protect their data will be sovereign."

One option Johnson is considering is imposing a market share cap on Huawei, in a bid to avoid over-reliance on the Chinese company, according to the Financial Times.

On Sunday, Brexit Secretary Stephen Barclay said he was confident the UK and US would get a post-Brexit trade deal done despite the tensions over Huawei.

"The key issue in terms of the US trade deal is the clear intent of the Trump administration to have a trade deal with the UK," Barclay told the BBC's Andrew Marr show. "They've been very clear in terms of how they prioritise that - that they want to have that deal. So yeah, there's issues in terms of 5G, but that is a UK decision."

Johnson may also this week decide on whether to proceed with the controversial High Speed Two rail link from London to the north of England, whose costs have spiralled.

Barclay said his "gut feeling" was that HS2 would go ahead, as it would play a key part in delivering on Johnson's pledge to level regional inequality.

Officials will announce plans this week to renationalise the troubled Northern Rail franchise which is operated by Arriva, according to reports in British newspapers over the weekend.

As the UK prepares legally to leave the EU on Friday, the government will also take steps to relax visa rules for top scientists, while clamping down on low-skilled migration after Brexit.

Immigration was a key issue during the 2016 referendum and Johnson, who led the campaign to exit the bloc, is proposing a points-based system that prioritises higher-skilled workers.

On Sunday, Home Secretary Priti Patel warned UK businesses they would have to change their approach to recruitment after Brexit. "They have been far too reliant on low skills and, quite frankly, cheap labour from the EU and we want to end that," she told Sky's Sophy Ridge show.

Patel said she would accept the findings of a report she commissioned by the Migration Advisory Committee, due to be published this week. The committee is reviewing a proposed 30,000-pound (S$53,000) minimum salary threshold for migrant workers that has alarmed businesses.

An increase in anti-immigrant rhetoric since the Brexit vote has alarmed business executives used to decades of unfettered movement of staff between the UK and the continent.

Industries such as construction, hospitality and the National Health Service are especially at risk from a lack of skilled foreign workers.