A Scottish Tory MP has warned supporters of leadership frontrunner Boris Johnson about trying to “subvert” the contest through tactical voting.

Stephen Kerr, who is supporting Michael Gove in the race to succeed Theresa May as Conservative leader, said it would be “very dangerous” if some of Johnson's backers voted for a rival they do not see as a threat in the final run off.

Six Tory MPs - Johnson, Gove, Sajid Javid, Dominic Raab, Rory Stewart and Jeremy Hunt - are still in the running to replace May as leader and Prime Minister, after she quit in the wake of failing to push through her Brexit deal.

MPs will whittle down the list to two and Tory members across the UK will vote to pick the winner.

In the first round of voting last week, Johnson trounced his rivals and is all but guaranteed a place in the final two. Hunt came second and Gove was a close third.

However, allies of Gove believe Johnson would rather face Hunt, who voted Remain in the EU referendum, in the members’ vote, rather than their man.

They believe Johnson would expect to be put under greater pressure by Gove, who worked closely with the former London Mayor in the pro-Brexit campaign.

Insiders fear that Johnson’s initial lead is so big that he may “lend” some MPs to Hunt in the next round of voting by Westminster colleagues.

Kerr, who represents Stirling, said: “It is a very dangerous thing for them to try and do, first of all. Trying to subvert the contest is not the right thing to do.”

He added: “Any attempt to try and subvert the contest would be a mistake.”

Meanwhile, Raab has hit out at Johnson by saying the party does not need a leader who could be seen as part of the "privileged elite".

The former Brexit secretary poured scorn on Johnson's reluctance to appear in the television debates, questioning whether he had the "mettle" to be prime minister.

He also attacked his plan for a tax cut for people earning over £50,000 - contrasting it with his own proposal to help those on low income.

The six remaining candidates to succeed May are due to appear before a hustings on Saturday organised by the National Conservative Convention representing the party grassroots.

Johnson has made it clear that he will not be taking part in the first TV debate on Channel 4 on Sunday.

He said however that he would appear in the second debate on the BBC on Tuesday after the field has further slimmed down following the second round of voting.

It followed criticism that he has been seeking to avoid media scrutiny amid fears of throwing away a seemingly unassailable lead.

Raab said it was essential that all the contenders for No 10 were thoroughly tested in the heat of debate.

"Everyone is going to have to demonstrate that they have not just the vision but the nerve and mettle to deal with the EU and with a minority government," he said.

"If you're not up for the TV debates and the test that provides, people will argue it's a barometer for what would happen if you get the job.

"If you can't take the heat of the TV studios what chance of taking the heat of the negotiating chamber in Brussels?"

Raab, who needs to add to his first round tally of 27 votes if he is to continue after the second round, also contrasted his background as a grammar school boy and the son of a refugee with ex-public school rivals like the Old Etonian Johnson.

"When you campaign in marginal seats, who can reach out and unite the working class vote and the middle-class vote?" he said.

"Are we going to be in a better position to do that with a candidate who isn't so easily caricatured as being from the privileged elite, with the son of a refugee, a grammar school boy who is offering tax cuts to most of those people on £15,000 as opposed to people on £50,000 and above?"

In another development, there was anger at a reported plan for the other contenders to pull out this week with only Johnson's name going forward to the final ballot of grassroots members in July.

The Daily Telegraph reported that the scheme had been hatched in the Tory whips' office in an attempt to avoid weeks of damaging "blue on blue" attacks by the rival candidates which would simply provide ammunition for Labour.

Such a move would be highly controversial within the party following criticism of the "coronation" of May, without giving the members a chance to vote, after Andrea Leadsom withdrew from the 2016 contest.

Stewart tweeted: "Please write to your MP if you think this is not a good idea and please RT (retweet) if you think anyone else might think this is not a good idea...."