The president of Expo Milan 2015, Diana Bracco, has been placed under investigation for tax evasion and embezzlement in relation to her role as CEO of Italian healthcare group Bracco Spa.

The case, involving alleged fake invoices for more than €3m (£2.1m, $3.3), is not connected with the universal exhibition that opened in the northern Italian city earlier this month, prosecutors said.

Detectives claim that between 2008 and 2013, a series of works on private properties (houses and boats) belonging to Bracco and her late husband, Roberto De Silva, were fraudulently invoiced to the namesake company she runs.

Bracco denies any wrongdoing, with her lawyer, Giuseppe Bana, saying "there was not tax fraud".

Bana claimed that the alleged irregularities have already been settled with Italy's tax agency, leaving no grounds for criminal proceedings against his client.

The lawyer also told IBTimes UK there was no reason for Bracco to step down from her role at Expo as the tax probe had nothing to do with the nutrition-themed fair.

"The issue doesn't even arise," he said. "The final decision is hers but my advice as a lawyer is she has no reason [to resign]".

Bracco has not been charged but authorities seized more than €1m pending further developments.

Another three people, the CEO of Bracco Real Estate Pietro Mascherpa and architects Marco Pollastri e Simona Calcinaghi are also under investigation.

Bracco is a prominent figure in the Italian business world. She was appointed president of Expo 2015 Spa, the company managing the universal exhibition, by the Italian government in 2008.

The six-month event, involving some 145 countries, had earlier been marred by a corruption scandal which eventually resulted in construction delays.

Originally established as a pharmaceutical company in 1927, Bracco Spa has since expanded to other healthcare branches and currently operates in 90 countries worldwide, according to its website.