In North America, there are several ABs that are internationally recognized, that is, direct signatory status in ILAC and/or APLAC for laboratory accreditation.
They are: IAS, A2LA, NVLAP (all U.S. based) and SCC (Canada.
Either should be able to provide the accreditation you seek.
I suggest talking to ALL before settling on one.....ask hard questions (what member of staff is assigned to the file, scheduling availability, costs to obtain/maintain accreditation, who makes decisions on the issuing of the accreditation, questions of that nature).....then contact accredited labs of those ABs.....not just EMC, but branch out and ask others also.....the service they received is what you can expect.
Hope this helps.
Hershal