European Union leaders will pledge on Wednesday to stand united in "constructive" talks with Britain on its exit from the EU to reduce uncertainty for citizens and businesses, a draft document showed just hours before London's formal notification to quit.

The draft does not mention the possibility that the two sides will fail to reach an agreement by the end of the two-year period envisaged by EU law. This removed a remark from an earlier version that the EU would be ready for a "no deal" option though it did not desire it.