A senior Stormont civil servant has warned it is "almost impossible" to have post-Brexit checks in place at NI ports and airports by January 2021.
Denis McMahon is the Permanent Secretary at the Department of Agriculture.
He said it was a "monumental challenge" to have new port checks by the time the Brexit transition period runs out at the end of this year.
He was speaking at Stormont's agriculture committee.
Mr McMahon said that his staff were working hard to meet the deadline but he said it was "almost impossible" and he said "we still lack a great deal of clarity".
He was quizzed on the ongoing UK/EU talks and said it was difficult to work out how these discussions would conclude.
He told one assembly member: "Your interpretation is as good as mine".
Robert Huey, the Chief Veterinary Officer for NI, explained that preparations were being made and staff were being recruited and facilities at the ports were being planned.
He said the department was facing "a huge amount of difficulty".
Mr Huey told MLAs that time was running out.
"It is almost too late standing on hilltops shouting at each other," he said.
"We need to fix this."
'Rob Peter to pay Paul'
Mr Huey also raised the issue of recruiting additional staff and said at the moment he had to find the additional money from existing budgets.
"I will have to rob Peter to pay Paul," he said.
Mr McMahon explained that the NI Agriculture Minister Edwin Poots was "opposed to additional checks" at local ports, but said the DUP minister understood that goods "must enter Northern Ireland legally".
Mr McMahon said his department had been placed in an "impossible position", but that his staff were working hard to make sure they abided by the law and had agri-food checks in place by January.
He said work would be done on time, although he predicted that "not everything will be in place".
He also warned MLAs that due to the timescale and the lack of clarity, the facilities at the ports "may not look pretty".
Last week, BBC News NI revealed the contents of a letter from the UK Environment Secretary George Eustice to Mr McMahon.
The letter said checks should be put in place without delay and delivery was critical.
Mr Eustice stated that the moves were in accordance with the Northern Ireland Protocol.
Tenders for the work at a number of sea ports were made made public last week and bids are to be made by later this month.
It is estimated that the work at places such as Belfast port, Warrenpoint and Larne could cost about £45m.