LONDON, Feb. 9 (Xinhua) -- Britain's chief Brexit negotiator David Davis responded Friday after the European Union (EU)'s Michael Barnier warned of talks over a future trade deal failing, with the prospect of customs border posts built between the Irish Republic and Northern Ireland.

Barnier, in Brussels, outlined his views of talks in London this week over a deal between the two when Britain leaves the EU in March 2019. His comments prompted a harsh reply in London from the Brexit Secretary Davis.

The Guardian newspaper described the day's events as a war of words between the two over Brexit transition claims. The rival Independent, in its take on a day of cross-channel disagreements, said relations between Britain and the EU had sunk to a new low as Davis and Barnier traded barbs.

Financial commentators reported that sterling dived after Barnier's comments, with the currency closing to 0.8 percent down against the U.S. dollar on Friday afternoon.

Keir Starmer, shadow Brexit secretary for the main opposition Labour Party at Westminster, described Barnier's comments as a wake-up call for Prime Minister Theresa May.

Starmer said: "It's vital the government secures sensible transitional arrangements to prevent a cliff-edge for our economy. Yet with just a few weeks until the March deadline, it's clear the government is no closer to reaching an agreement.

"Businesses and trade unions have been crystal clear that failure to secure strong transitional arrangements will mean companies pulling investment and staff out of the UK."

BARNIER: TRANSITION PERIOD "NOT A GIVEN"

The British government wants to negotiate a transition period of around two years to enable trade with the EU to continue after the two sides part company next year.

Labour's Starmer wants Britain to remain in a customs union with the EU and within the single market during a transition period.

In his media briefing in Brussels Friday, the EU's chief Brexit negotiator Barnier warned that a transition period is "not a given", saying substantial disagreements remained. Barnier also said he had some problems understanding Britain's position.

Barnier said talks over a UK-EU transition period could fail after exposing deep divisions over freedom of movement of EU citizens.

He said: "If these disagreements persist, the transition is not a given. Time is short, very short. We haven't a minute to lose if we want to succeed."

Barnier also said Britain's decision to leave the European single market and the European customs union would make border checks unavoidable between Ireland and Northern Ireland.

DAVIS: "FUNDAMENTAL CONTRADICTION" IN EU'S APPROACH

Davis hit back saying: "Given the intense work that has taken place this week it is surprising to hear that Michel Barnier is unclear on the UK's position in relation to the implementation (transition) period. We are seeking a time-limited period that maintains access to each other's markets on existing terms."

Davis added: "There is a fundamental contradiction in the approach the commission is taking. Today they acknowledged that a way to resolve disputes and infringements is needed. Yet at the same time they dismissed the UK's push for reasonable safeguards to ensure our interests are protected. It is not possible to have it both ways."

Both sides say they want to agree the transition period before the European Council meeting in March, giving them just under two months to make a deal on the issue.

The Daily Telegraph commented that Barnier's comments will spook British and foreign businesses, which have demanded certainty over the status of Britain after the March 2019 deadline.