Holidaymakers have been rushing to change up their travel money ahead of the EU vote.
Post Office Travel Money, which accounts for one in four of all UK foreign exchange transactions, said currency sales overall have surged by 74% year-on-year since the weekend.
It said on Tuesday that Post Office branch sales were up by 48.8% on the same period a year ago, while online purchases were up by 381%.
The value of the pound has see-sawed amid the uncertainty over whether the UK will decide to remain in the EU or vote for a Brexit.
There have been warnings that a Brexit vote could trigger further falls in the pound - and some holidaymakers may be hedging their bets by changing their money ahead of the vote.
International money transfer specialist HiFX reported the number of holidaymakers buying euros and US dollars has increased by 46% since the weekend.
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