A sign for a Brexit auction is seen at sunset in the border town of Jonesborough, Northern Ireland, November 29, 2017. REUTERS/Clodagh Kilcoyne

BRUSSELS (Reuters) - British and EU negotiators have made little progress this week on efforts to avoid a post-Brexit hard border in Ireland, a senior EU official said on Thursday.

“Progress so far seems elusive and substantive progress even more so,” the official told reporters, saying a key problem was London’s insistence on proposing solutions that would treat Northern Ireland as part of the whole United Kingdom.

Referring to British media reports, the official said the British side did not raise the possibility of extending a post-Brexit transition period beyond 2020 and also said Britain had not threatened to withhold funds it has already agreed to pay on withdrawal over a dispute over future British access to the EU’s Galileo navigation satellite programme.