According to TMZ reports:

Rapper Trina allegedly cost a concert promoter THOUSANDS of dollars this month … after no-showing at a performance in St. Louis … but Trina insists the promoter’s full of crap.

TMZ has obtained several letters sent to Trina’s booking agent — by the promoter’s lawyers — and according to the docs, the rapper was paid $7,000 to perform at a club called Imperial Palace in St. Louis on May 19th.

According to the letters, Trina’s team informed the promoter there was a scheduling conflict — but the rapper never formally canceled in writing, so the promoter went full steam ahead with the event.

Needless to say, May 19th rolled around — and Trina was nowhere to be seen.

The promoter tells TMZ, the event went on without Trina — held as a regular party at the club with DJ music — but people were pissed … and several demanded refunds.

Now, the promoter tells us, she’s planning to sue Trina for at least $16,000 — which includes Trina’s $7,000 fee, promotional costs, and other damages.

Trina’s rep tells TMZ, the rapper did agree to perform the gig — but cancelled long before the event due to other obligations … and even tried to return her $7,000 advance. Trina’s rep says the promoter refused to accept it.

What’s more, Trina’s rep believes the promoter falsely advertised the event as a Trina concert, knowing in advance Trina wouldn’t be performing. Trina’s rep says the rapper is now weighing legal options of her own.