"We have been informally approached by the IAAF (International Association of Athletics Federations) saying that this is by definition, a breach of the regulations. We have informed our athletes about this," Anders Albertsson, general secretary of the Swedish athletics federation, told a huddle of reporters outside the Luzhniki stadium.
"The code of conduct clearly states the rules do not allow any commercial or political statements during the competition."
Albertsson said the Swedish delegation had not put pressure on Green-Tregaro to change the colour of her fingernails, but "understood from Swedish media her nails are now red."
"If she knows she might be breaking the rules, that's a decision she takes, we don't have any objections on how they paint their fingernails," Albertsson added.
Tregaro's discreet support on Thursday during qualifying prompted Russia's pole vault champion Yelena Isinbayeva to brand her "disrespectful to our country".
Isinbayeva, an ambassador for next year's Winter Olympics to be staged in the Russian Black Sea resort of Sochi, ignited a media storm by saying she supported the controversial law.
She backtracked the following day when she said she had been "misunderstood" after making her comments in English.
The legislation, which was passed in June, outlaws some aspects of the promotion of homosexuality and has become a political hot potato ahead of the Sochi Games, when it will apply to athletes and spectators.
The International Olympic Committee (IOC) are seeking clarification from Russia on how the law will be applied.
(Editing by Alison Wildey)
