Lily Allen has reported an online spat with a man claiming to be a serving soldier, leading to a Ministry of Defence investigation.
The row started after a Twitter user, who said in his profile he was in the Army, told the singer he had "just seen you bought s*** I meant adopted a child from Africa".
Lily, who is a regular tweeter under her married name @lilyrosecooper, reported the comment to the MoD.
An Army spokesman said: "Racism of any kind is completely unacceptable and the Army has a zero-tolerance approach to all forms of harassment and discrimination.
"We are aware of the alleged offensive comments and are investigating the matter. It would be inappropriate to comment further while this is ongoing."
The Smile singer is no stranger to Twitter rows.
Last year she used the micro-blogging site to snub Piers Morgan's offer to appear on his Life Stories series and she has also clashed online with Cheryl Cole.