The pound slumped to its lowest level since October on Monday, following indications from Prime Minister Theresa May that Britain is heading for a so-called "hard Brexit".
Sterling fell a cent against the greenback to 1.21 dollars and was also trading down against the euro at 1.15.
On Sunday Mrs May said the Government is "working to get the best possible deal" for the UK on the issue of trade.
But she stressed the importance that will be given to gaining full control over immigration during divorce negotiations with Brussels.
Pressed on the issue of single market membership, the Prime Minister said some people had suggested the UK could "keep bits" of EU membership as it looks to leave the bloc.
Mrs May appeared to shut down that possibility as she said: "We are leaving. We are coming out. We are not going to be a member of the EU any longer."
The pound has dropped around 18% against the US dollar and 10% versus the euro since the June 23 vote as traders expect the British economy to be significantly weaker once it quits the European Union.