Поздравляю! [paz-drav-lya-yoo] Taken from: http://learningrussian.net/congratulations_verbs.php

you can say "мои поздравления" [mai paz-drav-'le-ni-ya]

nb. поздравляю is a verb. я поздравляю тебя - I congratulate you. strictly speaking, congratulations is поздравления - paz-drav-'le-ni-ya (noun in plural)

"Прими мои поздравления! " ( PRIMI MOI PO-ZDRAV-LYE-NIYA ) " Искренне рад за тебя! Поздравляю ! " ( IS-KRYEN-NYE RAD ZA TYE-BYA ! PO-ZDRAV-LYA-YU ! )

Usually more correct is "Поздравляю" / "Поздравляем" (as verb, for example: "Поздравляем с приобретением") or "Поздравление" / "Поздравления" (as noun).