The statement continued that the racist abuse was clearly heard by four Italian Football Federation observers at the match and that they came from "90 percent of the 16,000 fans in those areas of the ground".

Lazio have some of the most right-wing supporters in a country where fascist groups are a widespread phenomenon, including at Roma whose hardcore fans also have a long history of far-right links.

Wednesday's incidents were the latest in a long line involving Lazio, who had been given a suspended one-match stand closure in April last year following anti-Semitic and racist chants during another derby with Roma.

Their supporters also brought France international Samuel Umtiti to tears last January during a match at Lecce.

It's not the first time Lukaku has been targeted by fans in Italy, as he was racially abuse by Juventus fans last season and monkey chanted at by Cagliari supporters in 2019, while still at Inter Milan.

The incident at Cagliari, which went unpunished by authorities, was then followed by Inter's hardcore fans writing an open letter to Lukaku in which they said monkey chants weren't racist.

Lazio were also fined 50,000 euros for supporters breaking through a security cordon separating rivals fans in the stadium and launching "beer and water bottles, flares, fireworks and firecrackers" at the Roma section, whose fans cost their club a 15,000 euro fine for responding in kind.

Home supporters also threw flares and bottles on the pitch during the match, one full beer hitting Roma midfielder Edoardo Bove on the neck after he was substituted in the second half.

The Rome derby is one of Europe's most heated and there were a series of scuffles and police charges before Wednesday's match, while afterwards Lazio fans raided a pub popular with Roma fans near the stadium, stabbing two people during the melee.