MEXICO CITY, Dec 15 (Reuters) - Mexico’s central bank said on Tuesday that it is willing to collaborate with Congress over a controversial new cash law it opposes. Banxico, as the central bank is known, said in a statement it was open to contributing to the construction of a legal framework that benefits those who “legitimately receive foreign currency in cash”. (Reporting by Sharay Angulo; writing by Cassandra Garrison; editing by Drazen Jorgic)