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The government has prepared a short three-line bill to begin the Brexit process - so Theresa May can meet her March deadline, it is understood.

Sources say they believe the legislation is so tightly drawn it will be difficult for critical MPs to amend.

Ministers have drawn up the legislation in case they lose their appeal to the Supreme Court - which would force them to consult Parliament.

The High Court ruled against the government earlier this month.

Sources say the government would plan to introduce the bill in the Commons immediately after the Supreme Court ruling.

The hope would be to push the bill through the Commons in two weeks.

It would then go to the House of Lords where it is understood the government hopes peers would back down.

They believe peers would not dare defy MPs - if the Commons had approved the legislation.

Sources say they have devised the bill to be "bomb-proof" to amendments.

This would mean Mrs May could meet her March deadline for triggering Article 50 of the Lisbon Treaty, which begins the formal negotiation process.

Sources say although they looked at allowing Parliament a vote through "a substantive motion" rather than legislation, they decided this would leave them vulnerable to further legal challenge.