THERESA May will later today face Tory concerns over extending the Brexit transition period as Downing Street made clear it was just an “idea” and discussions about it with Brussels were still at an early stage.

The Prime Minister is due to take MPs’ questions following an update on last week’s European Council. Before she does, Commons Speaker John Bercow has granted two Urgent Questions on aspects of the Brexit process.

Tory Brexiteer John Redwood, the former Cabinet minister, will ask about the costs of staying in the EU's customs union and the withdrawal agreement while Tory Remainer Dominic Grieve, the former Attorney General will ask about whether the "meaningful vote" on any Brexit deal will be on an amendable motion, giving MPs the option to influence the Government's approach.

Scottish Conservatives are alarmed at the prospect of extending the transition or implementation period as, they feel, this would renege on a promise to the UK fishing industry to end it in December 2020.

Any extension, even by three months as mooted by Dominic Raab, the Brexit Secretary, would mean a full year’s extension as fishing quotas are set in December for the following year.

Last week, Scottish Secretary David Mundell contacted Number 10 to express his concerns, insisting that any extension to the 21-month transition period had to have an opt-out for the fishing industry from the CFP.

Yet, Scottish Tory MPs have privately admitted it would be highly unlikely the EU27 would agree to this.

Some have already warned they could vote down the Brexit deal if Mrs May went ahead with an extension to the transition period in the face of opposition from her own Scottish colleagues. It has even been suggested it could be possible that Scottish Tory MPs could vote down the Chancellor’s Budget.

They fear that any "betrayal" of the fishing industry, most of which is in Scotland, could have serious political ramifications for the party north of the border ie they could lose seats.

Asked about a possible fishing industry exemption to a transition extension, the PM’s spokesman said: “This is at the stage where it’s an idea. If it were to go forward it would be subject to negotiation and all those matters are subject to negotiation. The point is we are at the stage where this an idea and we are at the initial stages of discussion.”

Karen Bradley, the Northern Ireland Secretary, when asked about the subject at the British-Irish Parliamentary Assembly in London, said: "Now, we are looking at that. It is early days. It is a suggestion that has been put forward by the EU.

"And I want to be clear that we are committed to everything that we have agreed to in the joint report and we will ensure that there is no border on the island of Ireland."

She described the UK Government's commitment to the Belfast Good Friday Agreement as “absolute,” adding: “There is no reneging on any commitment to that agreement."

Meanwhile, MPs seeking a vote of confidence in Mrs May risked seeing Britain leave the EU without a deal, Chris Grayling, the Transport Secretary, has warned.

The Brexiteer, who ran the PM’s leadership campaign in 2016, appealed for calm as her opponents ramped up their threats to remove her from office if she did not alter course on Brexit.

Asked about a possible no-confidence vote, Mr Grayling told BBC Radio 4's Today programme: "This is really a moment for calm, level heads.

"We have got to get through the last bit of negotiation. There will be a vote in Parliament that follows.

"The reality is that, if the deal on offer is something that can't get through Parliament, we will end up in a no-deal situation, so it is in everyone's interest, the European Union and us, to make sure that what we agree is something that both sides can accept."

Mr Grayling explained that he would be willing to accept a "short bridge" backstop if Brexit negotiations were not complete by the end of the transition period.

He told Today: “There are two years to sort out the details of what comes next", but added: "I'm perfectly happy to contemplate a short bridge between the end of the implementation period and the start of the future economic partnership if it is necessary.

"I don't think it needs to be necessary, I don't want it to be necessary, because what it can't do, it absolutely can't do, is trap us in limbo indefinitely, and Cabinet is completely united about that," he added.

In Brussels, Brexiteers and former Cabinet ministers Iain Duncan Smith and Owen Paterson denied undermining the PM after a meeting with Michel Barnier, the EU’s chief negotiator.

Mr Duncan Smith said: "We are presenting some ideas which we think are constructive and we had a constructive discussion. Now we are going to go back and talk to the Government about it."