Britain's former finance minister Rishi Sunak again topped the latest vote by Conservative MPs to choose a new prime minister, as another candidate was eliminated to leave three contenders in the race.

Sunak garnered 118 votes, followed by former defence minister Penny Mordaunt on 92 and Foreign Secretary Liz Truss on 86, with longshot candidate Kemi Badenoch trailing on 59 and therefore eliminated from the contest.

The vote means that Britain will get either its first British Asian prime minister or the third female leader in the country's history.

Sunak, whose resignation helped to topple outgoing leader Boris Johnson, fell two votes short of the number needed to guarantee a place among the final two, who will battle it out over the summer before party members choose the winner.

He is all but guaranteed to make the final cut in Wednesday's last round of voting by MPs.

But the race to join him further tightened, with Truss making up five votes on Mordaunt - the one-time bookmaker's favourite.

Truss is now only six behind, and will hope that the right wing of the party swings behind her following the departure of Badenoch, a favourite of the grassroots members.

A YouGov poll published before the vote showed that Badenoch would beat the remaining candidates with the all-important members, and that Sunak would lose to them by wide margins.

Mordaunt had headed the same poll previously.

She now trails Truss after a damaging few days in which her former boss, one-time UK Brexit pointman David Frost, slammed her work ethic and questions were raised over her stance on trans rights.