The race to replace Boris Johnson as Conservative Party leader and the next British prime minister widened further on Monday as Foreign Secretary Liz Truss became another high-profile contestant entering the fray to go head-to-head with British Indian former minister Rishi Sunak.

Truss' junior minister in the Foreign, Commonwealth and Development Office (FCDO), Muzaffarabad-born Rehman Chishti, also entered the contest to become the second Pakistani-origin minister alongside UK-born former Health Secretary Sajid Javid.

It takes the total number of candidates to 11, including Indian-origin Attorney General Suella Braverman, Iraqi-origin Nadhim Zahawi, Nigerian-origin Kemi Bedanoch, Tory backbencher Tom Tugendhat, former foreign secretary Jeremy Hunt, Trade Minister Penny Mordaunt and Transport Secretary Grant Shapps.

Another senior Indian-origin candidate considering a leadership bid is UK Home Secretary Priti Patel, who is expected to pitch herself as a committed Brexiteer and is reportedly looking to bring other Brexit hardliners, like Braverman and Badenoch, into her camp.

It comes as the 1922 Committee of backbench parliamentarians, in charge of setting the rules and timeframe for the Conservative Party leadership election, will be holding a crucial meeting later on Monday. The rules of the game and the deadline for a final list of initial candidates will become clearer at the end of those discussions, chaired by senior Tory MP Sir Graham Brady.

It will be a two-stage process, with Conservative MPs whittling down the field to two final candidates through successive rounds of voting, before the wider Tory party membership elect their winner. It is expected that the new party leader and prime minister will be known by early September.

Meanwhile, using the tagline "Trusted to Deliver", 46-year-old Truss said in her campaign video that she wants to give people "the opportunity to achieve anything they want to achieve" regardless of their background and has pledged to cut taxes from day one .

"Colleagues know I mean what I say and only make promises I can keep. I can be trusted to deliver," said the minister with considerable support within the Tory ranks.

She now joins Sunak as the early frontrunners of the race and are likely to face off on the issue of taxes, with the 42-year-old former Chancellor maintaining that tax cuts would have to wait until the economic situation and inflation stabilises.

I'm incredibly thankful for the support I've received so far from my colleagues. I believe with your help we can restore trust, rebuild the economy and reunite the country, Sunak said in his Ready4Rishi campaign update.

For a traditionally low-tax favouring Conservative Party, the focus of the race is expected to be on the candidates' plans to cut taxes.

Launching his campaign with a video on Facebook, the other new candidate in the race 43-year-old Rehman Chishti said: "For me, it's important to ensure everyone who works hard, who's determined, who perseveres, that they have a government that is on their side, and that means lower taxes, small state, big society."

Meanwhile, Opposition Labour leader Sir Keir Starmer took aim at all the leadership hopefuls for signing up to "unfunded spending commitments", describing them as taking part in an "arms race of fantasy economics".