The new leader of the UK's governing Conservative Party who will succeed Boris Johnson as the British Prime Minister will be announced on September 5, the body responsible for the Tory leadership elections said on Monday.

The 1922 Committee of Conservative backbench MPs set out the timetable and rules of play for the elections, which will officially open and also close for nominations on Tuesday.

So far, 11 candidates led by frontrunners such as British Indian former minister Rishi Sunak and Foreign Secretary Liz Truss have declared their intention to contest.

We are very keen that we get this concluded as smoothly, cleanly and rapidly as possible, said Sir Graham Brady, chair of the 1922 Committee.

"Certainly, we should have a conclusion and a new leader of the party elected and announced on September 5 The crucial thing is we've arrived at the point we're at and we now have a very clear plan to take things forward and resolve the leadership question," he said.

New regulations voted in by the committee during a crucial meeting earlier on Monday mean Tory members of Parliament who put themselves forward to become the leader of the Conservative Party must have the backing of at least 20 other Tory MPs to get on to the ballot. These candidates will then need at least 30 votes to proceed to the next round, or just under 10 per cent of Tory MPs.

The first ballot will be held on Wednesday and the second ballot on Thursday, when the field is expected to be narrowed down further. There is provision for further ballots next week if the race to get to the final two candidates does not conclude by the end of this week.

Many of the Conservative Party's 358 MPs are yet to declare who they will be supporting, with the shortlist likely to become clearer only as the week progresses.

After the field is whittled down to the final two candidates, they will tour the UK for hustings to campaign the nearly 200,000 Tory party members who will then vote for the winner based on a one member, one vote system. The candidate who receives the most votes will win the race and be declared the new Tory leader and UK Prime Minister.

PTI