Bastareaud will feature for France against England on Saturday
France coach Marc Lievremont has hit out after receiving letters claiming Guadeloupe-born back Mathieu Bastareaud shows a lack of allegiance to France.
Centre Bastareaud, one of France's top performers in this year's Six Nations, has been targeted in anonymous letters.
"They point out the fact that Mathieu Bastareaud is black, that he doesn't sing during the anthem and therefore he does not feel French," said Lievremont.
"There's no way to describe this kind of stupidity."
France captain Thierry Dusautoir, who was born in Ivory Coast, will lead the side out against England at the Stade de France on Saturday - where victory would assure the hosts a Six Nations Grand Slam.
And Lievremont, who in the past received similar letters criticising Basque-born back row Imanol Harinordoquoy, is adamant rugby will not entertain any racist behaviour.
"I get a few letters, obviously none of which have been signed because whoever sent them are scumbags and obviously not very brave," stated Lievremont.
"Rugby and sport in general also engenders showing tolerance and respect. Obviously it's not because Mathieu is black and comes from Guadeloupe that he doesn't feel French.
"Everyone approaches matches in a different way, and that includes with anthems. You have to respect that."
Meanwhile, Bastareaud and his France team-mates could already be Six Nations champions by the time they take to the pitch on Saturday night, should Ireland fail to beat Scotland three hours earlier.
Bastareaud started the tournament by scoring his first two international tries against Scotland in his first Test start since falsely claiming he had been assaulted during France's tour of New Zealand last summer.
The 21-year-old alleged he was set upon by a group of men outside his hotel after France's 14-10 defeat by the All Blacks in Wellington, but he later admitted he had lied to cover up a drink-related facial injury.
"I think I have grown," insisted Bastareaud. "That in the game I'm raising my head more, physically, mentally. I feel better and you can see that on the pitch."