A Sinn Fein politician has said he would be nervous about agreeing to a Northern Ireland-only backstop, in case it sent the wrong message to the Conservative Party.

The idea was first floated by the Irish premier on Thursday morning while on radio on Ireland’s state broadcaster RTE’s Sean O’Rourke show.

Taoiseach Leo Varadkar said there was a possibility that the backstop could only apply to Northern Ireland, but added that such a deal would not go down well with the Democratic Unionist Party (DUP) and it was the UK Government’s insistence that the backstop should apply to the UK as a whole.

The issue is a red line for the DUP because the unionist party believes it could threaten the integrity of the UK if it created divergence between Northern Ireland and Great Britain.

Mr Varadkar added he wanted to hear from the next British prime minister to discuss detailed plans.

Sinn Fein TD Eoin O’Broin cautioned the Irish premier on floating any ideas that may bolster the Conservative Party into thinking Ireland can be swayed on the issue.

“The Taoiseach (Leo Varadkar) needs to be very, very careful, I think given the level of cross-party cooperation on this, if he’s going to change the government’s position on something as fundamental as the backstop, he’d be much better speaking to party leaders first before floating ideas publicly,” he said.

“I would be very, very nervous about anything that gives the Tory party, who are already in such disarray, the idea that a little bit more pressure might push the Irish government even further away from the position we’ve all held until now.

“I think our party spokespeople would like to hear the detail of what the Taoiseach is talking about before we sign up to anything.

“Our position remains unchanged, we want the single market, we want the customs union, but crucially the backstop has to stay.

“I think any shift from the current position would embolden the Tories further and I think that would be a bad idea.”

Tory leadership frontrunner Boris Johnson has said he wants to scrap the backstop.