Brexit day: Prime Minister Theresa May tells parliament that Article 50 has been triggered
UK Prime Minister Theresa MayReuters

An European Union (EU) document has stated that Britain will have to settle the bills of its separation from the EU in euros, not pounds. "An orderly withdrawal of the United Kingdom from the Union requires settling the financial obligations undertaken before the withdrawal date," said the European Commission document.

"The agreement should define the precise way in which these obligations will be calculated... the obligations should be defined in euro," it added.

The document however did not mention exactly how much would the Brexit settlement cost Britain, although EU officials previously laid out the estimated figures to be around 60 billion euros. The estimated cost has sparked outrage in London, which had put the estimated cost to be around 20 billion euros, AFP reported.

The document titled "Non-Paper on key elements likely to feature in the draft negotiating directives," was drawn up for the EC, which will conduct the Brexit negotiations with the UK.

The document covers the same points which were outlined by the EU president Donald Tusk in response to UK Prime Minister Theresa May's official notification of triggering Article 50.

Article 50 is a 265-word passage of the Lisbon Treaty which states how a EU member can leave the bloc voluntarily. The Treaty forms the constitutional basis of the EU.

The European Union leaders from all the 27 member states will hold an emergency summit on April 29, where exit negotiations with the UK are expected to be discussed. Reports state that the formal negotiations are not likely to take place until after the French presidential elections on May 7, 2017.

After the countries finalise their objectives for Brexit, these instructions will be given to the European Commission's chief negotiator Michael Barnier. However, it could be weeks before the formal talks of the negotiations begin as the European Parliament will likely want a say in the talks.