Mohamed Mansour, who served as transport minister under the late Mubarak - who was deposed during a popular revolution - became the party's treasurer last December.

Mr Mansour said he had donated the amount - reported by the Daily Telegraph as the largest the Tories have received for more than 20 years - because of his "confidence" in Rishi Sunak.

Writing in the Telegraph, Mr Mansour said: "I believe that this country has a very capable prime minister. One who understands how growth is generated in the modern economy. He gets the importance of technology and innovation. He can make the modern economy work for all UK citizens.

"My confidence in the prime minister is why I was proud to become a senior treasurer of the Conservative Party last December.

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"I want to give him the best chance of having a full five-year term and so have donated £5m to the party's election fighting fund. I look at what he has achieved in his first months in office and think what he could do in five years."

Sky News' Westminster Accounts project, in conjunction with Tortoise Media, collated all the information on donations that is available through Parliament's register of interest for the first time in one database, with total sums and details of which MPs are receiving how much money and from whom.

It revealed that Mr Sunak received the highest number of donations of any Conservative MP with £546,043 - but he came behind Labour leader Sir Keir Starmer, who amassed £752,809 given to him by 67 companies and individuals.

This latest donation to Mr Sunak will not show up on the Electoral Commission's register until next month, meaning it won't yet be available on the Westminster Accounts tool.

The development will be a welcome boost for Mr Sunak, who presided over a punishing set of local elections that saw the Tories lose more than 1,000 seats.

Despite the result, Mr Sunak confidently backed himself to remain prime minister for another term in an interview with Sky political editor Beth Rigby from the G7 summit in Japan.

Asked whether he would still be PM after the next general election, Mr Sunak replied: "Yes. I'm working really hard to deliver for the British people.

"That's my priority, that's what I am thinking about. I'm confident we can deliver for people. I know that things are tough right now, but I think we have made good progress in the six months that I've been in the job. I'll just keep at it."

According to Forbes, Mr Mansour oversees family conglomerate Mansour Group, which was founded by his father Loutfy in 1952 and has 60,000 employees.

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From 2006 to 2009, Mr Mansour served as Egypt's minister of transportation under Mubarak, who was topped in 2011 as Egypt was caught up in a wave of popular uprisings that became known as the Arab Spring.

Mubarak, known by his nickname as the modern-day "pharaoh", ruled Egypt as an autocrat for three decades from 1981, and was jailed for years after the revolution that ended his rule.

He was given a life sentence for the deaths of anti-government protesters at the heart of the uprising and was convicted in 2015 alongside his two sons, Alaa and Gamal, of embezzling millions of pounds from the state.

Mubarak eventually walked free in 2017 after being acquitted of the majority of the charges against him in a move that shocked Egyptians.

He died on 25 February 2020.