There has been "practically no movement" on the Irish border issue over the summer, a member of the European Parliament's Brexit steering group has said.
Danuta Hübner was speaking to the parliament's Constitutional Affairs committee.
She said the EU's chief negotiator Michel Barnier had offered "some openness" to make the border backstop more acceptable to the UK.
However, no solution has yet emerged.
The backstop is the arrangement which will apply if the Irish border cannot be kept as frictionless as it is now in the context of a wider deal.
The EU has proposed a backstop that would mean NI staying in the EU customs union, large parts of the single market and the EU VAT system.
The UK government has rejected it as a threat to the integrity of the UK, and has suggested a backstop that would see the UK as a whole remaining aligned with the EU customs union for a limited time after 2020.
Ms Hübner said the border remains the toughest issue for the Brexit withdrawal agreement.
Any deal between the EU and UK will need to be approved by the European Parliament.