Organizers of an Italian half-marathon have backed down after their decision to ban African athletes from participating sparked outrage and led to allegations of racism.

The head of the May 5 race in Trieste, northeast Italy, had claimed the controversial decision was made to highlight an exploitative "trade" in African athletes.

But the ban has been reversed after prompting fury from several politicians, who attacked the choice as racist and condemned prominent far-right politicians for stoking such cases of racial division in the country.

"This year we have decided only to take European athletes to make the point that measures must be taken to regulate what is currently a trade in high-value African athletes," race organizer Fabio Carini told newspaper La Repubblica on Saturday.

He added that African athletes "are purely and simply exploited, which is something we can no longer accept."

The reasoning was labeled an "ignoble, shameless excuse" by Italian MEP Isabella De Monte, while Nicola Fratoianni, secretary of the Italian Left party, called on Italian and international sports bodies to "speak up and take action."

"It is evident that this choice goes against every rule, value and ethical code of the world of sport. As well as against common sense," Fratoianni added.

Italian sport has been wracked with a series of racist incidents in recent months, with various spurts of racial abuse by soccer fans drawing condemnation on almost a weekly basis.

In the most recent flare-ups, Lazio supporters hung a pro-Mussolini banner and made fascist salutes on the streets of Milan on Wednesday, before launching racist abuse at AC Milan player Tiemoue Bakayoko during a game between the two sides.

Carini announced the U-turn later on Saturday, admitting in a statement that the issue had been mishandled.

"I recognize that we should have raised the problem in different times and ways and that's what we I am sorry for the reactions that this choice has raised," he said on the race's Facebook page.

"I apologize to those who have honestly felt offended," he added.

But he took a more defiant tone on his own Facebook page, saying the decision had opened "Pandora's (box)" and adding that he organizes a race "for the love of an often-ungrateful city."

And his climbdown did little to appease critics, who linked the rhetoric and policies of far-right politicians in Italy's government to the increasing regularity of race rows in Italian sport.

"It has just been discovered that the organizer of the #TriesteRunningFestival is a fan of #Salvini ... Who would have thought," Italian MEP Giuseppe Ferrandino wrote on Twitter, referring to Italy's hardline Interior Minister Matteo Salvini.

The half-marathon is the culmination of the four-day Trieste Running Festival, which begins on Thursday. (CNN)

Update news