1. A method for creating or updating parallel corpus in a machine translation system, comprising the steps of: preparing a test set, E, to be updated; translating the test set E from a first language to a second language using a translation method other than parallel corpus, so as to create set F in the second language; translating set F back to the first language using a translation method other than parallel corpus so as to create set E′ in the first language; computing confidence scores for the translation of each item in the set based on the similarity of E and E′; creating a subset, H, of the highest confidence scores; and adding the translations in subset H directly to the parallel corpus without first presenting the translations to a human translator for correction, wherein the parallel corpus is stored in memory on the machine translation system.