London: Links between the alleged spy Anna Chapman and a controversial Zimbabwean businessman are being investigated by MI5.

The Russian redhead at the centre of the American espionage probe worked with multi-millionaire Ken Sharpe for three years at a UK-registered company based in the London flat she shared with her then husband, Alex.

Chapman revealed yesterday that an MI5 agent who called herself ‘Clare' spent much of a five-hour interrogation last week asking him about his ex-wife's relationship with Russian-speaking Sharpe.

During her time with the company, Southern Union, the 28-year-old moved millions of pounds between Zimbabwe and the United Kingdom, raising questions over whether the cash may have been laundered for the purposes of espionage.

The MI5 agent also quizzed Chapman, 30, about Sharpe's close relationship with Chapman's father, Vasily Kushchenko, a top Russian diplomat accused last week of involvement with the KGB.

According to Chapman, it was Kushchenko who first introduced his ex-wife to Sharpe, 38, whose businesses include property development and a plant exporting vodka bottles to Russia.

Sharpe is a fluent Russian speaker who lives in his native Zimbabwe with Russian wife Joanna.

Chapman claims that his ex-wife and Sharpe set up Southern Union, which has charitable status, to enable Zimbabwean expats to send money home at competitive exchange rates.

Chapman was made a director of the company but was asked to leave just one month after he split from his wife in 2005.

He said his interview with the MI5 agent on Monday had covered his "life with Anna" but that the conversation had repeatedly returned to her father and, in particular, Sharpe.

However, Sharpe denied the claims and said: "I have not heard from MI5. Southern Union in the UK was not my company."

Southern Union is still registered as an active company at Companies House. Its sole current director is Steven Sugden, who lives in Dublin. Sugden has denied any involvement with the company and said he had been listed as a director without his knowledge.