Boris Johnson has pleaded with MPs to back his Brexit deal and "heal the rifts in British politics" ahead of a set of momentous Commons votes.

The House is convening on a Saturday for the first time since the Falklands War after the Prime Minister reached a new withdrawal agreement with Brussels.

Addressing MPs on Saturday morning, Johnson said the deal he struck with the EU will allow the UK to leave "whole and entire" on October 31.

He said any further Brexit delay would be "corrosive", however, MPs could force Johnson to formally request a further Article 50 extension in votes later in the day, which appear to be on a knife edge.

An amendment by former Conservative minister Sir Oliver Letwin would withhold approval of the PM's deal until the withdrawal agreement has been implemented into law in full by MPs.

If a deal is not approved by Saturday night, Johnson is required by law to write to Brussels and ask for a three-month Brexit delay.

Number 10 has threatened to send Tory MPs home and effectively cancel a meaningful vote on the deal if the Commons passes the Letwin amendment.

Sir Oliver, who had the Tory whip withdrawn after rebelling over Brexit, said his amendment was an "insurance policy" to prevent Britain "crashing out" without a deal on October 31.

Meanwhile, the SNP's Westminster leader Ian Blackford accused Johnson of striking a deal that "shafted" Scotland.

Opening the historic proceedings in the Commons, the Prime Minister called on MPs to reconcile over Brexit and deliver on the result of the 2016 EU referendum.

Johnson said: "The House will need no reminding that this is the second deal and the fourth vote, three-and-a-half years after the nation voted for Brexit.

"And during those years friendships have been strained, families divided and the attention of this House consumed by a single issue that has at times felt incapable of resolution.

"But I hope that this is the moment when we can finally achieve that resolution and reconcile the instincts that compete within us."

He urged MPs to unite behind his deal to "heal the rifts in British politics", adding: "It is my judgement we have reached the best possible solution.

"I must tell the House, in all candour, whatever letters they may seek to force the government to write, it cannot change my judgement that further delay is pointless, expensive and deeply corrosive of public trust."

Labour leader Jeremy Corbyn said his party could not back a deal he claimed was even worse than Theresa May's deal - rejected three times by MPs.

Corbyn told MPs: "It is not a good deal for our country and future generations who will feel the impact. It should be voted down.

"I totally understand the frustration and the fatigue across the country and in this House.

"But we simply cannot vote for a deal that is even worse than the one this House rejected three times."

Echoing the Labour leader's comments, Blackford said: "The Prime Minister has returned from Brussels to present a deal that he knows, that we all know, is actually worse than Theresa May's deal.

"A deal that would see Scotland shafted by this United Kingdom Government, left at an economic disadvantage, with Scotland's views totally disregarded by this Prime Minister and his government."

The SNP's Westminster leader said Johnson's statement to MPs did not contain a single mention of Scotland, while it had 13 references to Northern Ireland.

He added: "Despite the fact that the Scottish people, like the people of Northern Ireland, voted overwhelmingly to remain in the European Union, this Prime Minister has never entertained the notion of giving Scotland the same arrangements that Northern Ireland gets in this deal.

"The truth is, this Prime Minister doesn't care about Scotland.

"He and his government have treated the Scottish Government, our Scottish Parliament and the Scottish people with nothing but contempt.

"Not a single MP who cares about Scotland's future should consider supporting the Prime Minister today."

Responding to Blackford, the Prime Minister said: "I must say that I think he's being a little bit... churlish in his response because after all I didn't mention England and I didn't mention Wales.

"The reason of course that Northern Ireland is a particular subject of discussion, it is a legitimate point, is that there are particular circumstances in Northern Ireland at the border which deserve particular respect and sensitivity."

Both the final vote on the deal - if it gets that far - and the vote on the Letwin amendment are expected to be very close.

Johnson's former allies the DUP have vowed to vote down his deal due to new arrangements on the Irish border which keep Northern Ireland in economic alignment with the Republic of Ireland.

Without their support, the Prime Minister needs the backing of former Tory rebels who he expelled from the party as well as hardline Brexiteers within his party, and a number of pro-Brexit Labour backbenchers.

The SNP, the Liberal Democrats and the Labour frontbench have all promised to vote against the deal.