The European Union's chief Brexit negotiator said there were still differences for London and Brussels to overcome on Britain's divorce bill, the Irish border and citizens’ rights.
Speaking at a business conference in Berlin, Michel Barnier said that negotiations would continue before a 4 December meeting between British Prime Minister Theresa May and European Commission President Jean-Claude Juncker.
Mr Barnier said that the EU had to be, and was, united in dealing with Britain on its withdrawal and warned that failure to reach agreement would be very bad.
"No deal would be a very bad deal," Mr Barnier said, switching from French to English in a speech to Germany's BDA employers association.
Mr Barnier also said he hoped to have made progress on the principles of Britain's divorce from the EU by next week and that London knew it could not have one foot in the single market and one foot out of it.
The UK's reported increased Brexit deal financial offer is set to put new focus to Irish issues at next month's EU Summit.
The offer is said to have been given a broad welcome by the EU and is being seen as a breakthrough ahead of next month's EU summit at which the UK is hoping to get the go-ahead to start the next phase of talks on future trade ties.
Meanwhile, the European Commission for Agriculture Phil Hogan has said that Britain has made proposals on its Brexit divorce bill that come "very close" to meeting the EU's terms and will "hopefully" meet its requirements on the Irish border.
"I would welcome very much the fact that the United Kingdom has brought forward proposals that go very close towards meeting the requirements of the EU 27 member states... in order to reach agreement on the first part of the agenda" concerning the financial settlement, Mr Hogan told a news briefing.
However, EU negotiators say more progress needs to be made on the border and on citizens' rights before trade negotiations can begin.
If there is an acceptable formula on the table to plug the hole in the EU's budget, attention will shift to items two and three on the agenda - citizens' rights and the border on the island of Ireland.
To date, the British government has produced no detailed plan on how to address the border question.
It is increasingly likely that tension between Dublin and London will surface at the EU meeting.
Last weekend, DUP leader Arlene Foster said Northern Ireland could not have any trade barriers placed between it and the rest of the UK.
In London yesterday, Sinn Féin's South Down MP Chris Hazzard said there could be civil disobedience if customs posts appeared on the border as normal people in civic society are very, very angry.
Tory MEP Charles Tannock yesterday suggested Northern Ireland should have a referendum to decide if it remains in the EU's customs union and single market.
Mr Tannock was a prominent Remainer in the Brexit referendum campaign.
Conservative MP Andrew Bridgen has said the "eye-watering sum" of the so-called Brexit divorce bill is to "ensure that it is no one else can afford to leave".
Speaking on RTÉ's Today with Seán O'Rourke, Mr Bridgen, who campaigned for the UK to leave the EU, said if the bill does not go through Parliament, the UK will exit on WTO terms and "have no bill to pay."
No need for Ireland to use veto - Varadkar
The Taoiseach has told the Dáil that he does not see a need for Ireland to use, or threaten to use, a veto to block the progression of Brexit negotiations.
He was responding to Labour Leader Brendan Howlin who asked for an assurance that EU negotiators would not move to phase two of the Brexit talks until the issues around the border are resolved.
Mr Howlin said the Taoiseach would need to "stand firm and not blink" in the face of pressure to move on the discussions without a deal on the border.
He also urged Leo Varadkar to brief opposition leaders in private on his strategy ahead of the EU summit next month.
Mr Varadkar said progress is being made on the border issue and "the solidarity that exists for Ireland to avoid a hard border is very strong".
"I am very confident that the EU council will operate by consensus, and there will be no need to use, or threaten a veto on that issue," he added.