The EU's chief trade negotiator Phil Hogan has warned that the riskiest part of the Brexit negotiations has yet to come and that a "crash-out" Brexit was still a possibility at the end of December.

In an interview with RTÉ News, Mr Hogan warned against complacency and urged people in Ireland to "come out of their slumber" and wake up to that reality.

He said: "I'm very concerned at what I see in Ireland the moment. There's a lot of complacency in the system. Commentators and the media and the public generally don't seem to realise we're starting the most difficult part of the negotiations."

Mr Hogan, who will be the lead negotiator in the free trade negotiations, said that if things had gone wrong in the first part of the negotiations, the Withdrawal Agreement then the manifestos in the Irish election would have been different.

"It was easy enough to get some compromises in phase one, relative to the interests of every member state, and the interests now of the UK with an 80 seat majority.

"If things had gone wrong in the first part of the negotiations, you can consider in the context of a general election what this would have meant for manifestos in terms of income, in terms of wages, in terms of jobs, the possible economic rupture in terms of a crash out Brexit.

"This this is still on the agenda," he said.

"The real cut off point is the 31 December 2020, not 31 January. So, people should come out of their slumber is some way and wake up to the reality that we're in the intensive phase of the negotiations and in the more risky part."

Speaking ahead of a vote in the European Parliament to ratify the Withdrawal Agreement, Mr Hogan told RTÉ News that the EU would insist on the UK signing up to level playing field commitments, in terms of labour, environmental, social, taxation and state aid standards.

"The more [the UK] diverge away from the single market… the more difficult it's going to be to have a free trade agreement. So, this means there will be a very difficult discussion that we will have to have with the United Kingdom government.

"But we remain optimistic at the end of the day [that we will] have the necessary trade-offs to strike a deal that's good for the EU, good for Ireland and good for the United Kingdom.

"If you go out of the single market and customs union on December 31 next as the UK are saying they will, then you're going to have difficulties with your nearest market, where they export 46% of their products if they're going to be diverting away from those rules.

"So, creating the level playing field, being as close as possible to the EU at the moment, is going to mitigate a lot of problems. That's up to the UK to make that choice. This is what the EU want, to be as close as possible in our trading relationship with the United Kindgom."

Mr Hogan said there was only the time available for "four or five" rounds of negotiation before the end of June, when the UK has to decide whether or not to extend the transition period.

"Prime Minister [Boris] Johnson has said he doesn't want to do so, and I have to take him seriously… in view of the fact that he has an 80 seat majority."

The EU would do its best to conclude an agreement by the end of the year, but it would have to prioritise, he said.

He added that the EU would adopt its negotiating mandate for the trade negotiations, and that "we'll get down to work the day after".

He said: "Both sides have cards to play, but perhaps the UK doesn't realise the EU might have more cards to play. So, time will tell in the context of the negotiations how the relationship will be, or the mood music in the negotiations."

Mr Hogan described this week as "a sad moment for the EU".

He told RTÉ News: "Many Irish people will be very sad at the outcome, that we do not have our nearest neighbour as part of the same negotiating team. For so many years we were always on the one side."