Lazio President Claudio Lotito has rallied against widespread criticism of the team's performance against Inter on Sunday by insisting "the sportsmanship and integrity of the club and players cannot be in doubt".
The Biancoceleste lost 2-0 to an Inter side who are challenging for the Scudetto against Lazio's bitter rivals Roma.
The home fans at the Stadio Olimpico were cheering for Inter, leading to accusations Lazio had rolled over to hinder Roma's title aspirations.
Roma were particularly vociferous in their criticism but Lotito was adamant there had been no foul play.
He said: "Lazio should not have to apologise to anyone but instead should receive apologies from those that, ignoring their own responsibility, have launched non-existent blame on others.
"Lazio and their fans do not accept insults and insinuations.
"The sportsmanship and integrity of Lazio and of their players cannot be in doubt."
The win moved Inter two points clear of Roma, whose President Rosella Sensi said: "After what we saw at the Olimpico, to call ours the most beautiful league in the world is a paradox.
"I would be ashamed to win that way."