By Agence France-Presse
"It is and will always remain a matter of deep regret to me that I have not been able to deliver Brexit," May, her voice breaking with emotion, said in a statement outside her Downing Street residence.
Britain's Prime Minister Theresa May announces her resignation outside 10 Downing street in central London on May 24, 2019. // AFP PHOTO
The resignation will signal the formal start of a leadership contest during which May would remain as caretaker prime minister.
"I will resign as leader of the Conservative and Unionist Party on Friday, 7th June," May said.
"The process for electing a new leadership should begin in the following week," she said.
The leadership race is expected to take several weeks.