The UK’s ambassador to France told MPs his staff are making contact with other candidates they had no plans to forge links with Ms Le Pen.
Lord Llewellyn, who was formerly David Cameron’s chief of staff in Downing Street, told the Foreign Affairs select committee: “With respect to the Front National, we have a policy of not engaging, there is a longstanding policy. That is the policy, which has been the policy for many years.
“We know who the candidate is on the centre-right, the candidate is Monsieur Fillon, obviously we have contacts with him and his team.
“On the left we don’t know who the candidate is going to be. We will know the answer on 29 January after the second round of primaries. My team is in touch with people across the picture on the left.”
Foreign Affairs select committee chairman Crispin Blunt said he was surprised at the Government’s position on Ms Le Pen considering she is riding high in the polls ahead of May’s elections.
There were a few red faces when Donald Trump won the US Presidential Election and Britain was accused of failing to build strong links with Republican nominee because he was considered such an outsider for the White House.
There are now fears the mistake could be repeated with the French but Lord Llewellyn has insisted any change in policy would be a “matter for ministers”.
Ukip foreign and commonwealth affairs spokesman James Carver said: “Have they learnt nothing from the election of Donald Trump? The global establishment widely condemned him but now, awkwardly, find themselves trying to build diplomatic relations with him and his team from an obviously uncomfortable position.
“It’s bad diplomacy not to consider all eventualities in the next French presidential election and with Ms Le Pen expected to at the least reach the final round run-off in May, our Government is refusing to engage with a politician who could become the President of a country just 21 miles away.”
Mr Carver has previously insisted Ukip MEPs should not sit in the same right-wing group as Ms Le Pen in the European Parliament.
But he said: “I certainly don’t condone either Ms Le Pen or her party but were she to do a Donald Trump, the diplomatic fallout in the UK would be embarrassing to say the least.”
Ms Le Pen is widely expected to make the final round run-off against one of the other leading candidates, most likely either centre-right Republican François Fillon or independent Emmanuel Macron.
The French firebrand has led efforts to improve the National Front’s image and now focuses on anti-immigration policies and her desire for France to quit the Euro.