"The withdrawal agreement remains the best and only deal possible… the debates and votes in the House of Commons yesterday do not change that. The withdrawal agreement will not be renegotiated," he said in the European Parliament.
The chances of a "hard" withdrawal of the United Kingdom from the bloc, that is, without a ratified agreement on the conditions of this process, increased after the Tuesday vote in the UK parliament, Juncker added.
The British parliament voted Tuesday on amendments that rejected a no-deal Brexit and authorized UK Prime Minister Theresa May to return to Brussels for more talks on a legally binding change to the Irish border proposal contained in the draft Brexit deal agreed by Brussels and London at the end of 2018.
On Wednesday, Irish Foreign Minister Simon Coveney also stressed that the withdrawal agreement between London and Brussels was not open for renegotiation.
The Irish border issue has been the stumbling block in the EU-UK Brexit talks. Both sides have been seeking to avoid the hard border on the island of Ireland, expressing concerns that it may shatter the hard-won peace in the region. In November, Brussels and London agreed on the Brexit deal, including the so-called backstop that would be put into practice if the sides failed to agree on all the terms of their relationship by the end of the Brexit transition period.
The backstop would keep the United Kingdom in single customs territory with the bloc, while Northern Ireland would be aligned to some of the EU single market rules. The UK parliament however rejected the draft Brexit deal mainly due to the backstop earlier in January.