Bruno Mars is declaring war on his music publisher -- claiming the company refuses to let him out of his contract ... even though he has already delivered on his end of the bargain.
Mars has filed a lawsuit against Bug Music, Inc. -- claiming the company failed to pick up the option on his contract after he delivered an agreed upon number of songs.
In the documents, filed today in L.A. County Superior Court, Mars claims he turned in all of his music by February -- at which point, Bug had a certain amount of time to exercise its option to continue the relationship with Mars.
Bruno claims Bug never got back to him ... so he considered the contract terminated.
According to the docs, the honchos at Bug believe Mars is wrong -- and insist he is still under a contract which gives them 50% of the copyrights of any music Bruno makes.
Now, Mars says ... he needs a judge to issue a declaration that his contract is in fact over -- so he can move on with his career.
We called Bug for comment -- but they didn't want to talk.