Visitors to the five-star Waldorf Astoria have been bemused by a sign on the front desk that values the Scots pound at $1.3387, compared to the $1.3429 it is offering for a Bank of England note.
Stewart Hosie, the SNP Treasury spokesman, said: "This is a very unfair situation, which Scottish holidaymakers to various parts of the world will sadly have experienced for themselves.
"It highlights the deficiencies of the current arrangements, and one of the opportunities for a formal sterling area between an independent Scotland and the rest of the UK will be to bring Scottish notes into parity with English ones once and for all."
The hotel is understood to have told its currency information supplier that the two types of sterling were "completely different", adding that despite the notes being "interchangeable over there [in the UK] ... they are not the same". The UK Treasury said there was no economic reason for dealers to offer different rates.