Irish Prime Minister Leo Varadkar believes the European Union has the upper hand in upcoming trade negotiations with Britain after Brexit, he said in an interview broadcast yesterday.

Varadkar argued the size of the EU, which will comprise 27 countries once Britain has left on Friday, means it holds more sway in talks with London over their future relationship.

The Irish leader, who is fighting a general election on February 8, also cast doubt on finalising a free trade deal this year, as insisted on by his British counterpart Boris Johnson.

"We (the EU) have a population and a market of 450 million people. The UK, it's about 60 (million)," Varadkar told BBC television.

"So if these were two teams up against each other playing football, who do you think has the stronger team?"

Varadkar, who played a pivotal part in the first phase of UK-EU divorce talks, met the bloc's chief Brexit negotiator Michel Barnier in Dublin on Monday.

The Irish leader added in the interview that Brussels would not accept anything less than a comprehensive free trade agreement with Britain moving forward.