The British government has still failed to present any alternative to the Irish backstop in Brexit talks, the EU has said - amid warnings that the bloc is running out of patience with the UK.

A spokesperson for the European Commission told reporters in Brussels on Monday afternoon that the British government had not suggested how any replacement could actually work.

“At a point enough is enough,” Dutch trade minister Sigrid Kaag told newspaper Het Financieele Dagblad.

“At that stage the certainty of deterioration might be better than continuing without perspective. At a certain point there must be clarity. A good reason is needed for a new delay. What? It is difficult to say categorically.

“You have to see the context and see if there is a realistic expectation that this will lead to a follow-up phase. But so far, the British have not presented an alternative to the Brexit agreement that is already in place.”

Speaking during a visit to Dublin on Monday Boris Johnson said Britain would be "producing ideas on how to take this forward", telling reporters: "Angela Merkel said 30 days should be enough. I think she's totally right."

Ms Merkel however made her comments on 21 August, 19 days ago.

When asked whether he has any alternative the backstop Mr Johnson said he did, but that he would not share them now.

The delays come amid leaks from Downing Street suggesting that the government is treating the talks in Brussels as "a sham" and not interesting in coming to a conclusion.

David Frost, the UK's chief negotiator, is due to return to Brussels on Wednesday for further meetings with Michel Barnier's team at the European Commission.

Speaking at the European Commission headquarters in Brussels, a spokesperson for the EU's executive said UK officials had come up with plans on how Northern Ireland could have a say in any new backstop replacement - but now what the backstop replacement might actually be.

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"What I can tell you from the technical talks that happened here last week is that the UK has presented some ideas on how any all-Ireland sanitary and phytosanitary (SPS) solutions could involve the agreement of Northern Ireland. These sanitary and phytosanitary (SPS) solutions themselves were however not presented. Technical meetings will continue this week," she said, adding that there would be no "running commentary" on talks.