The move will pave the way for a leadership battle for her successor who will try to deliver Brexit after May failed to get her deal through Parliament.
May announced her resignation May 24, saying it was a matter of deep regret that she had been unable to deliver Brexit.
Eleven Conservative MPs are vying to replace her, including former Foreign Secretary Boris Johnson, but some are likely to drop out before the June 10 deadline for nominations, the BBC reported.
May remains acting party leader while the contest takes place. Her time as leader had been dominated by Brexit, with her party divided over the issue.
Nominations for her successor will close on June 10, with the first round of voting by MPs taking place on June 13. Following a hustings involving the remaining candidates on June 17, the second ballot will take place on June 18.
Up to five MPs' ballots are expected to take place, with the two candidates left standing announced on June 20. They will then go forward to a ballot of Tory Party members, with the winner expected to be announced by July 22.
The UK was originally meant to leave the European Union on March 29 but that was then postponed to April 12 and eventually to October 31.
When May announced her resignation, she said it was time for a new Prime Minister to try to deliver Brexit.
( With inputs from IANS )