British Prime Minister Theresa May on Friday set an exact time for the U.K. to leave the EU.
May gave 2300GMT on March 29, 2019, as the precise hour Britain would end its 46-year membership of the union.
The detail will be set out in an amendment to the EU Withdrawal Bill that will be examined by lawmakers next week.
Writing in The Daily Telegraph newspaper, May warned against any attempts to sabotage the U.K.'s exit from the EU, known as Brexit. The latest round of negotiations with EU officials are due to start later Thursday.
"Let no-one doubt our determination or question our resolve, Brexit is happening," May said. "It will be there in black and white on the front page of this historic piece of legislation: the United Kingdom will be leaving the EU on March 29, 2019, at 11 p.m. GMT."
She added: "We will not tolerate attempts from any quarter to use the process of amendments to this Bill as a mechanism to try to block the democratic wishes of the British people by attempting to slow down or stop our departure from the European Union."
