The EU will try to call Theresa May’s bluff later and warn that it could walk out of Brexit negotiations.

According to a leaked draft of a joint statement to be issued later, the EU will also act “as one” against the UK in a bid to minimise the damage caused by its departure from the bloc.

Theresa May has sent official divorce papers to Brussels.

But the process of the UK's withdrawal will not official begin until the document is in the hands of the President of the European Council, Donald Tusk, just after noon.

Mr Tusk is then due to deliver a statement just as Mrs May sets out the details of the letter to MPs at around 12.30pm.

A leaked version of Mr Tusk's speech, seen by the EURACTIV website, also shows that EU leaders will attempt to agree wide-ranging arrangements for the UK's exit,before beginning discussions on future trade deals.

Mr Tusk is expected to say that the first priority is to “minimise the uncertainty caused by the decision of the United Kingdom for our citizens, businesses and member states”.

“Therefore, we will start by focusing on all key arrangements for an orderly withdrawal.”

But he will also say that while the EU is keen to strike up a fruitful future trading relationship with the UK after Brexit it is “ready” for the talks to fail.

The “European Union is ready for such an outcome even though we do not desire it".

Mrs May has previously threatened to walk out on negotiations, saying that no deal would be better than a bad deal with the EU.

However, earlier this month the Brexit Secretary David Davis admitted to MPs that the government did not know whether or not that statement was true.

A detailed assessment of which would be worse, a bad deal or no deal, will not be finished until next year, he suggested.

Earlier, the Chancellor Philip Hammond said that the Conservative Government’s Article 50 letter had set the "right tone" for exit talks.

Once the official process of withdrawal from the EU is triggered negotiators have just two years to hammer out a deal.

However, the EU’s chief negotiator has suggested that politicians will have less than the full 24 months to reach an agreement, because of the time needed to get the plan through the European Parliament.