Downing Street is in talks with Macquarie Group, the Australian lender, to secure a £10 billion investment in UK infrastructure, which would represent one of the largest such commitments ever made by a foreign company.

Sky News has learned that Number 10 officials have been negotiating with bank executives over the plan – which would be for energy and digital infrastructure projects – for several weeks.

An announcement was due to be made during a state visit to Australia by the Prime Minister, which had been tentatively scheduled for the middle of this month.

The trip has now been postponed due to Mr Johnson’s domestic crisis and growing challenges on the international stage, but is expected to be rearranged if he survives the immediate threat of a leadership challenge, insiders say.

Sources said the £10billion figure included a range of renewable energy investments, a number of which have already been publicly announced by Macquarie, as well as several new projects in the energy and utilities sectors. communications infrastructure.

Macquarie has become a prolific investor in Britain, claiming to have invested more than £50bn in UK infrastructure projects in recent years.

In 2017 he bought the government’s Green Investment Bank in a controversial deal that has been accused of cheating UK taxpayers.

The GIB has since been renamed Green Investment Group, which forms the bulk of Macquarie’s renewable energy development division.

Securing major investment controls for Britain’s infrastructure has become a top priority for Downing Street officials as they seek to demonstrate Mr Johnson’s ability to act as a post-Brexit magnet for foreign capital.

Macquarie has a range of assets in the UK, including KCOM, a fiber optic network in Hull and East Yorkshire, and a significant stake in Southern Water.

His role in accelerating fast fiber and renewable energy to parts of Britain plays into the Prime Minister’s leveling policy at a time when Mr Johnson is fighting to show that his national program has not not been completely derailed by the Downing Street lockdown breaches scandal.

A source said Macquarie was due to announce the £10bn of new investment at a time coordinated with ministers.

The bank directly employs around 2,000 people in Britain and another 18,000 in the businesses it owns.

A source said Macquarie’s new £10bn investment would be a combination of capital from the Sydney-based lender’s own balance sheet and funds it manages.

Macquarie has British roots, being formed from the Australian branch of Hill Samuel, a London merchant bank, in 1969, before changing its name to Macquarie in 1985.

It opened its first UK office in 1989.

The UK signed a free trade deal with Australia in December, with the government saying it would unlock £10.4bn of additional trade.

Mr Johnson had joked that a trade deal between the two countries would give Britons access to “reasonably priced Tim Tams”, a reference to the famous Australian biscuit.

Ministers called the deal “historic” as it was the first to be negotiated from scratch since Britain left the European Union.

Last month, Liz Truss, the Foreign Secretary, traveled to Australia to meet officials – a trip that has since come under scrutiny due to the estimated £500,000 cost of her flights on a government plane.

In a statement to Sky News, Macquarie said: “The UK is one of the best places in the world to invest and ever since.

“It is our hub for operations in Europe, the Middle East and Africa and we are proud to have invested over £50 billion in critical infrastructure in the UK in recent years.

“Over the next few years, we will advance significant new investment in communities from Southampton to Orkney, in vital new infrastructure from offshore wind to super-fast broadband.”

This weekend, Downing Street declined to comment.