British Prime Minister Theresa May said Friday that the European Union and the United Kingdom are at an "impasse" in talks over Brexit.

The U.K. leader reiterated that she will not overturn the result of the 2016 referendum and "nor will I break up my country."

Speaking from inside Number 10 Downing Street, May repeated that the options on offer from the EU were unacceptable and would "make a mockery of the referendum we had two years ago."

May also called on the EU to provide more detail on its negotiating position.

"Yesterday, (European Council President) Donald Tusk said our proposals would undermine the single market. He didn't explain how in any detail or make any counter-proposal. So we are at an impasse."

In an apparent jab at the tone of other European leaders during negotiations, May added that healthy future relations were at risk.

"Throughout this process, I have treated the EU with nothing but respect. The U.K. expects the same. A good relationship at the end of this process depends on it," she said.

Sterling had fallen almost 1 percent in trading Friday prior to the speech, and was down to 1.3 percent at the end of May's statement.