Former cabinet minister David Lidington has said there will have to be "some kind of direct rule" for Northern Ireland ahead of Brexit.
Stormont has been without an executive for more than two years and Parliament has had to pass some key legislation for Northern Ireland in the interim.
The UK is due to leave the EU at the end of October.
Mr Lidington said if there was no deal, it would be unconscionable to leave part of the UK without real governance.
The Conservative MP, who was in charge of overseeing Brexit preparations for devolved nations in Theresa's May's government, made the comments on the BBC's Today programme on Saturday.
"There will have to be some kind of direct rule and, I think, it's important that the government gets that sorted and in place, before the end of October, that deadline," he said.
"At the moment, the Northern Ireland civil service has no power to do things like give emergency support to farmers or food producers whose supply chains into the Irish Republic could be completely killed by a no-deal exit.
"All of a sudden their customers south of the border would say: 'Sorry you haven't got the certification. It's no longer an EU product, I can't legally buy this from you anymore'.
"The civil service of Northern Ireland does not have any power to help in those circumstances or to take other emergency measures that would be needed in the event of no deal.
"I think it would be unconscionable to leave any part of the United Kingdom without proper governance in the circumstances of that kind of crisis and for Northern Ireland, in particular, where the politics is fragile, the case is stronger than anywhere else to get this sorted in advance."
Speaking on the same radio programme, DUP MP Sir Jeffrey Donaldson said his party was "ready to go into government tomorrow, we have no preconditions".
"We are ready to serve the people of Northern Ireland in a government," he added.
But, he added: "If Sinn Féin continue to refuse to do that, then someone is going to have to start taking decisions. We cannot allow the people of Northern Ireland to continue to be disadvantaged because of Sinn Féin's refusal to share power."
However, Sinn Féin MP Chris Hazzard said that the idea of direct rule "underscores once again that the dysfunctional Tory government is in complete hock in this grubby little deal with the DUP".
'Send a clear message'
Mr Hazzard told the same programme: "People again on this side of the Irish sea in Ireland are completely bemused at the chaos, the dysfunction and reminded again that their interests will never be served at Westminster."
SDLP leader Colum Eastwood told BBC News NI it was up to the DUP and Sinn Féin to get back into government.
Mr Eastwood accused the two parties of handing "power away from local politicians".
"Now they can protest about that. If they want to do something about it, they should get into government - that's how we solve this issue.
"That's how we send a very clear message to London that we are not having a crash-out Brexit."
Stormont's power-sharing government collapsed in January 2017 amid a bitter row about a green energy scheme.
Parliament is due to be suspended next week, returning a fortnight before the Brexit deadline, which some MPs say will cause problems for Northern Ireland.
There are questions about what might happen if the government needs to pass any urgent legislation to mitigate a no-deal Brexit in Northern Ireland.
Earlier this week, Conservative MP Simon Hoare was backed by Mr Lidington in warning that if Stormont was not restored by 31 October, NI civil servants would not be able to take "any initiative" to off-set issues raised by a no-deal Brexit.
Northern Ireland Secretary Julian Smith has said that if talks to restore power-sharing did not succeed before Brexit, direct powers would need to be implemented "at pace".
In July, Mr Lidington, who was then the de-facto deputy prime minister, warned that a no-deal Brexit could lead to the break up of the union.