By Jan Strupczewski

The EU's executive said on Friday it was reassured that London was keen to step up the momentum of talks to implement the Withdrawal Agreement divorce deal agreed with Britain last year, but it warned that the window of opportunity was closing fast.

The European Commission's comments came ahead of a video-conference scheduled for Monday between British Prime Minister Boris Johnson and the presidents of the European Union's three main institutions to take stock of the Brexit negotiations.

"The window of opportunity to put in place the operational measures needed to ensure that the protocol can function as intended on the first of January 2021 is rapidly closing," European Commission Vice-President Maros Sefcovic said.

"We need to move from aspiration to operation and fast," he told a news conference after talks with British Cabinet Office Minister Michael Gove.

Britain left the EU in January. Their relationship is now governed by a transition arrangement that keeps previous rules in place while they negotiate new terms.

Sefcovic said Gove told him that London had no intention of extending the transition period beyond the end of this year, a prospect some fear may lead to a no-deal hard exit that could compound the economic damage caused by the coronavirus pandemic.

London and Brussels remain far apart on the issues of fair competition guarantees and the governance of their new relationship, as well as on fishing rights. In talks last week, negotiators made very little progress towards a free trade pact, but they did agree to intensify negotiations.

Sefcovic said he was hopeful that Monday's meeting between European Commission President Ursula von der Leyen and Johnson along with the European Parliament and European Council presidents would lead to "fresh momentum on the UK side".

"I believe that the set of activities we discussed today ... should provide us with adequate, also political, space to move into positive developments over the summer, because we know autumn is around the corner and January 1 is not far from that."

(Writing by John Chalmers; Editing by Hugh Lawson)