Deputy Howlin told Hot Press: "Words must mean something in international agreements, but in recent days we have seen efforts by senior UK Cabinet Ministers to resile from what has been agreed.
"The joint report on Friday clearly says in paragraph five that 'the joint commitments set out below in this joint report shall be reflected in the Withdrawal Agreement in full detail', while in paragraph 50 it committed that 'In the absence of agreed solutions, the United Kingdom will maintain full alignment' clearly outlining a fall back position in a hard Brexit scenario.
"As we saw in the Brexit referendum, the level of debate, and plain untruths told about leaving the EU now continue to infect efforts to negotiate an exit agreement.
"I am deeply concerned at the failure so far of the cabinet of Prime Minister Theresa May to meet and collectively affirm the agreement reached last Friday between the UK and EU.
"Despite the Taoiseach calling the agreement 'bulletproof', the EU Commission has now described it as a 'gentleman's agreement' while the Brexit Secretary described it as a 'statement of intent', later clarifying that it was 'legally enforceable."
Deputy Howlin said that clarification is also needed on the implications of the phrase 'all-island economy' as used in paragraph 49 of the Joint Report, and the reference by Prime Minister May today to 'economic cooperation across the island' and how it would be interpreted.
"The Irish Government must now seek binding reassurances from both the UK and EU that what was painstakingly agreed last week will be legally enforced and guaranteed to provide the commitment necessary to avoid a hard Border," he concluded.