"Mr Barnier clearly did not understand why Brexit happened," Farage, the former head of the UK Independence Party and still a member of the European Parliament, wrote on Twitter.
Britain voted to leave the European Union by a narrow 52 to 48 per cent margin in June 2016 after a campaign in which Farage played a key role.
Farage later said in a video message: "He doesn't understand for one moment that immigration was a big reason that we voted for Brexit. (It was) perfectly clear to me the British government hasn't even discussed the subject with him so far.
"We've given an awful lot already, and in terms of him giving a bit back, to make sure there's a deal on services and financial services, well, I wouldn't say it's a happy new year for the Brexit deal."
He added that the chances of Britain leaving in March next year without an agreement on future relations with the EU -- which would leave businesses subject to punishing World Trade Organisation tariffs -- "will increase" without a compromise from Barnier.
Barnier has travelled across Europe in recent months meeting governments to hear their wishes for the Brexit negotiations, but has also met several figures who are not directly involved in the talks, including British opposition Labour leader Jeremy Corbyn.
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