Media playback is unsupported on your device Media caption John McDonnell said the new leadership was "radicalising the Parliamentary Labour Party already"

Labour has denied that constituency boundary changes could be used as an excuse to deselect some of its own MPs in favour of more left-wing candidates.

Shadow Chancellor John McDonnell said there was "no way" this would happen and existing rules would apply.

But one former shadow minister said he feared the review could be "the means to remove MPs whose faces don't fit".

And veteran Labour MP Frank Field said there could be a revolt in the party if colleagues were "unfairly treated".

The boundaries used to elect MPs in May, which date back to 2005, will be reviewed ahead of the next election, scheduled to take place in 2020.

They could look very different by the time the changes are published in 2018 because of the reduction in the number of seats from 650 to 600.

Territorial changes

Analysis for the BBC's Sunday Politics - based on the latest boundary proposals from 2012 - suggests that MPs including Liam Byrne, Chris Leslie and Tristram Hunt on the right of the party could face significant changes to their current seats.

Of the 206 seats Labour currently holds in England, only 36 would remain unchanged, while 54 constituencies are likely to change by more than 40%.

The figure is more than double the proportion of Tory seats affected. From their 319 seats only 41 face similar pressure on their boundaries.

The current Labour rules, introduced in 2013, state that an MP with a substantial territorial interest in a new constituency may seek selection as a matter of right - a substantial territorial interest is defined as 40% or more of the previous constituency.

The BBC's political correspondent Ellie Price said she had been told by Labour's National Executive Committee that there were no plans to change existing rules but many MPs on the right of the party remain concerned.

Their fears were not allayed by the appointment of Seumas Milne as Jeremy Corbyn's new director of strategy and communications. A few weeks before he took on the job, he seemed to suggest boundary changes might offer an opportunity to select some different Labour members.

'Picked off'

Simon Danczuk. the MP for Rochdale who has suggested he could launch a leadership challenge to Mr Corbyn if Labour performs badly in next May's elections, told the Sunday Politics: "I think my colleagues are right to be worried about this. There has been an influx of people joining the party, some of them probably expelled in years gone by.

"Many will certainly be on the left of the party. They will be Jeremy Corbyn supporters and they will be making a decision because of boundary changes. And it's fair to say they may not pick more moderate MPs like myself."

Frank Field, who saw off attempts by his own party to deselect him in the 1980s, said any kind of change would have real ramifications.

"There will be a large group I would hope in Parliament of MPs who will, if colleagues are unfairly treated, encourage their colleagues to stand in by-elections, to stand as independent candidates and a large number of us including myself, would go and actually campaign for them.

"It's a capital offence to campaign for somebody standing against a Labour candidate but if enough of us go they can't pick all of us off and expel the lot."

'Radicalised'

Shadow Chancellor John McDonnell told the BBC's Andrew Marr that Mr Corbyn had made it clear that the existing rules for selecting MPs ahead of general elections would not be reviewed.

"We are opposing any threat to individual MPs," he said. "We are not in favour of reselection of these MPs. The democratic processes in the Labour Party will take place in the boundary commission in the normal way.

"There is no way we will allow MPs to be deselected in that way. We will work together on this."

But Mr McDonnell suggested MPs were already being "radicalised" and they would have to be "accountable" to new supporters who joined the party in large numbers in the past six months and helped propel Mr Corbyn to victory as well as older members.