The Prime Minister has written to Brussels to formally request a three-month delay to the UK's exit date from the EU.

Theresa May's letter to European Council president Donald Tusk asked for an extension to Article 50 until June 30 to give her enough time to pass a Brexit deal.

Last week, Parliament voted in favour of a Brexit delay and the Prime Minister told MPs that if they hadn't passed a deal by now, she would request a longer extension.

In her letter to Tusk, May said Speaker John Bercow's decision to rule out a third "meaningful vote" on the deal if the motion is not substantially different, meant she could not table her deal again this week.

But she said she still intends "to bring the deal back to the House" and told Tusk a longer extension would not be "in either of our interests".

The Prime Minister noted a prolonged delay would mean the UK having to participate in upcoming European Parliament elections.

Speaking in Brussels later on Wednesday, Tusk said a short Article 50 extension is "possible" but on the condition that MPs pass May's Brexit deal next week.

It comes ahead of the PM's attendance of a European Council summit on Thursday and Friday, where the remaining 27 EU member states will decide whether or not to grant a Brexit delay.

All 27 states must agree unanimously to allow the Article 50 extension, without which Britain will leave the EU by law on March 29.

Speaking at Prime Minister's Questions on Wednesday, May said: "The idea that three years after voting to leave the EU, the people of this country should be asked to elect a new set of MEPs is, I believe, unacceptable.

"It would be a failure to deliver on the referendum decision this House said it would deliver."

She accused Parliament of having "indulged itself on Europe for too long", adding: "The government intends to bring forward proposals for a third meaningful vote.

"If that vote is passed, the extension will give the House time to consider the Withdrawal Agreement Bill. If not, the House will have to decide how to proceed.

"But as Prime Minister, I am not prepared to delay Brexit any further than June 30."

The Commons has rejected May's withdrawal agreement on two occasions, the first time, in January, by a record-breaking margin of 230 votes.

It was voted down again this month - despite additional legal assurances agreed with Brussels on the Irish backstop - by 149 votes, the fourth biggest parliamentary defeat for a sitting government in history.

Responding to the Prime Minister's letter, the European Council president said the deal needed to be ratified by the Commons in order for a Brexit delay to take place.

Tusk said: "In the light of the consultations that I have conducted over the past days, I believe that a short extension would be possible.

"But it would be conditional on a positive vote on the Withdrawal Agreement in the House of Commons.

"The question remains open as to the duration of such an extension."

The SNP's Westminster leader Ian Blackford quoted May's effective deputy David Lidington as saying last week that a short, one-off delay to Brexit would be "downright reckless".

Replying to May at PMQs, Blackford said: "Her deal has failed. This House has voted against no-deal. Once again, the Prime Minister is acting in her own self-interest."

He added: "The people of Scotland deserve a choice over their future. If Westminster fails, Scotland will act."