As Africa’s only female head of state and a scientist of renown, Ameenah Gurib-Fakim was held up as an example of a modern, progressive leader, and the focus of more international publicity than her relatively small country, Mauritius, would normally receive.

But all that ended rather abruptly last week when she resigned as President after claims emerged of her shopping spree on jewellery and clothes costing thousands of dollars in Dubai and Washington DC. Her lavish purchases had been carried out using a platinum credit card supplied by a London-based charity, the Planet Earth Institute.

Ms Gurib-Fakim wanted to stress that the purchases were “inadvertent” and that she had repaid the money. Nonetheless, the incident has brought to light links between a Labour peer and the owner of a major Portuguese football club who had been under criminal investigation in Portugal in the past, but cleared.

The businessman is Alvaro Sobrinho who, it emerged, part-funded the Planet Earth Institute (PEI). The peer is Paul Boateng, formerly a minister in Tony Blair’s government and High Commissioner to South Africa. He is now a member of the House of Lords, and a trustee of the same charity, PEI.

An investigation by the European Investigative Collaborations network and The Independent has found lucrative business links between Mr Sobrinho and Baron Boateng of Akyem in the Republic of Ghana and of Wembley in the London Borough of Brent – a man who, it was once held, would be Britain’s first black prime minister.

There is no evidence of wrongdoing or that any dealings between him and Mr Sobrinho have involved illegal activity.

A consultancy firm Lord Boateng owns with his wife Janet, Akyem Law and Advisory Services Ltd, has, accounts show, made hundreds of thousands of pounds in profit. According to the parliamentary register of interests, its only client is a company called World Property SA, which is owned by Mr Sobrinho, and has received funding from Besa, the Angolan branch of Banco Espirito Santo (BES).

Mr Sobrinho, who owns the Portuguese football club Sporting Lisbon, which once had superstars such as Cristiano Ronaldo and Luis Figo on its books, was the chief executive of Besa from 2001 to 2012 and chair until 2013. Investigators have examined the alleged disappearance of $5.7bn (£4bn) from Besa’s books, but no charges have resulted.

The Angolan banker was not the only funder of PEI, set up to aid African science education, in its early years. Money also came from, among others, billionaire oligarchs Alexander Machkevich, Patokh Chodiev and Alijan Ibragimov, the “Kazakh Trio”, who made their fortune from the Russian metal industry following the collapse of the Soviet Union.

The grand opening of PEI took place in London. In July 2011 Mr Sobrinho attended the House of Lords, to showcase the inauguration of the charity’s scientific board with Lord Boateng and Lord Bruce Grocott.

That summer in Portugal, Mr Sobrinho was named by the prosecutor’s office in Lisbon as a formal suspect in a fraud case. Later that year, in November 2011, he became a formal suspect in a second criminal inquiry in the country when he was named in an alleged money laundering scam over the purchase of six apartments in a luxury building in Lisbon for nearly €10m (£8.7m). Mr Sobrinho denied any wrongdoing and no charges were brought against him.

Lord Grocott recalled that, as chairman of the All-Party Parliamentary Group on Angola, he was used to requests to meet with visitors from the region. However, he said it was unusual for a businessman to make such a request, and even less common for them to ask for a photo opportunity, as Mr Sobrinho did. “The photo was the only part that I thought was strange,” said Lord Grocott. “We did this one meeting for less than an hour and then I never heard from him again.”

In the spring and summer of 2012 Lord Boateng joined PEI as its trustee and started his consultancy firm, Akyem, with Mr Sobrinho’s World Property SA as a client. Akyem’s annual accounts show that at the end of its first year, it had had made £320,445 profit.

PEI gave evidence to the Commons International Development Committee’s inquiry into “post-2015 development goals”. On 5 June 2013, a consultation about mobile technology in education in Africa was held at the House of Lords with Lord Boateng and Mr Sobrinho in attendance along with Anat Bar-Gera, founder of an internet access provider named YooMee Africa, and Professor Tim Unwin, the secretary-general of the Commonwealth Telecommunications Organisation. Lord Boateng was, at the time, a paid advisor for YooMee.

Since his appointment as a trustee, Lord Boateng had made a number of trips abroad to promote PEI, including to New York and the Angolan capital Luanda where he had held meetings with politicians and businessmen.

Nearly 70 per cent of PEI’s cash appeared to have been spent each year in business meetings and conferences in Angola where trustees like Lord Boateng met ambassadors from Britain, Portugal and Zimbabwe along with representatives of private businesses such as BP, McKinsey, PetroAfrica, Eaglestone and Fesa, the foundation of then then President of Angola, Jose Eduardo dos Santos.

But it had been alleged that PEI had also taken on additional work for its trustee Mr Sorbinho. In 2014, Mauricio Fernandes, who was chief executive of PEI at the time, wrote in an email to Anat Bar-Gera, chair of YooMee Africa, where Lord Boateng has been an adviser since 2011, that PEI is “now coordinating Dr Sobrinho’s public profile”. He continued: “Toward the end of last year we took responsibility for a new and integrated programme of work relating to Dr Sobrinho’s public profile and this includes SEO activity, alongside numerous other services such as copywriting, media relations and legal PR advice.

“[Sobrinho’s new public profile] is in its early stages but … it’s already showing some positive signs, including better Google rankings and increased positive coverage through blogs, interviews and articles like Private Banker and the Financial Times’ This is Africa, and I’m very confidant [sic] this will only increase in coming months.”

In 2017 Ms Gurib-Fakim resigned as a trustee of PEI. Lord Boateng remains a trustee of PEI and his company Akyem continues to have World Property SA as a client.

Responding by email to questions about his links with Mr Sobrinho, Lord Boateng wrote: “I am as a matter of public record the chairman and founder of a company providing regulatory geopolitical risk and advisory services to a range of individuals and businesses on Africa. I do not comment on the business of my professional clients. Any suggestion that my relationship with Dr Sobrinho and his business was in any way improper has no basis in fact and would be wholly defamatory.

“The Planet Earth Institute and its sister foundation in Mauritius have a proven track record in the promotion of science education innovation and technology on the continent. I and my fellow trustees welcome the support of Dr Sobrinho for this and other charitable causes on the continent of Africa. I have nothing to add to the statement already issued by PEI on its website as to the circumstances surrounding the resignation of Prof Gurib-Fakim from its board.”