Web services compositions are defined using languages supporting the descrip- tions of orchestration and choreography. BPEL is the most well known and used orchestration language. It describes the behavior of the process that specifies the composition of web ser- vices but it does not support verification and validation of behavioral requirements. In our work, we are interested in the formal validation of web services orchestrations. We propose a proof and refinement based approach for the formal representation, verification and validation of web services compositions using the Event B method. This paper presents the BPEL2B translator that automates the translation of BPEL into Event B models.