Nastase, a former French and US Open champion, is currently at the centre of an International Tennis Federation (ITF) investigation following a series of controversial incidents during a Fed Cup tie with Great Britain last month.

The 70-year-old has been provisionally suspended by the ITF over comments he made about Serena Williams' unborn baby, which the American described as racist, and for swearing at Britain's Anne Keothavong and Johanna Konta and match umpire Jaume Campistol.

The former world number one, however, was part of the presentation party at the Madrid Open trophy ceremony as Romanian Fed Cup team member Simona Halep was crowned champion for a second year running.

Simon congratulated Halep and opponent Kristina Mladenovic of France for their "outstanding display of tennis" in the final, which ended 7-5, 6-7, 6-2.

He added that "the only shadow cast on the day" was Nastase's invitation to participate in the award ceremony.

"He had no place on court," he said in a statement on the WTA website.

"He is currently under a provisional suspension by the ITF for his prior offensive actions and we revoked his credential privileges at WTA events while the investigation is being completed."

Nastase has been banned from the French Open after his behaviour at the Fed Cup, while Wimbledon organisers have confirmed he will not be invited into their Royal Box on Centre Court. 

Simon spoke of his disappointment that the Madrid Open, a tournament owned and run by Nastase's fellow Romanian Ion Tiriac, had taken a more relaxed stance.

"It was both irresponsible and unacceptable of the Madrid Open to bestow him an official role," he added.

"The Madrid tournament is a Premier-level event and held to the highest standards of professional tennis and leadership which were not reflected."

The incidents involving Nastase took place at the Tenis Club IDU in Constanta.

During a pre-match press conference for the Fed Cup tie, Nastase was overheard saying "let's see what colour it has, chocolate with milk" about Williams' baby.

Williams, an African American, is expecting to give birth to her child later this year with her fiancé Alexis Ohanian, who is white.

At the same press conference, Nastase was heard asking a pregnant Keothavong, Britain's captain, for her hotel room number.

The following day, he was removed from the stadium during the second rubber between Konta and Sorana Cirstea after he swore at the world number six and her captain along with Campistol, which led to the match being suspended for 25 minutes.

Following this, the ITF confirmed they had banned him from the match, although Nastase did reappear at the tennis club the next day.

This came after he had stormed into the media room at the venue and shouted at British journalist Eleanor Crooks, the Press Association's tennis correspondent, following stories being published about his comments on Williams' baby.

During the outburst, Nastase called Crooks "stupid" several times.

Nastase, the men's singles runner-up at Wimbledon in 1972 and 1976, did apologise on his Facebook page for the incidents.