Britain's Prime Minister Theresa May holds a press conference at the end of the second day of the G7 Summit on June 9, 2018 in La Malbaie, Canada.

British Prime Minister Theresa May has warned rebels in her party that the alternative to her potential Brexit deal with the EU is no deal.

The United Kingdom is due to leave the EU on March 29 and yet little is clear: There is, so far, no full exit agreement and some rebels in May's Conservative Party have threatened to vote down a deal if she clinches one.

"I think that the alternative to that will be having no deal," May told BBC TV.

The main sticking point to agreeing a deal between Britain and the EU is the issue of ensuring there will be no hard border between Northern Ireland and the Irish Republic after Brexit.