Civil servants across Whitehall have been instructed to ramp up their emergency no-deal planning, with preparations including hiring staff for a 24-hour “emergency centre”.

The Department for Environment, Food and Rural Affairs (Defra), one of those likely to be worst hit by a no-deal Brexit, has advertised 90 new posts for civil servants to staff a crisis centre. The centre is being set up to plan for and manage “the reasonable scenario of no deal”, the job advert says.

The EU Exit Emergencies Centre is intended to be a temporary measure for three to six months. Staff will be expected to work shifts, to be on call 24/7 and will be trained in multiple roles, according to the job description.

“If you are on call and a situation arises that requires the mobilisation of the EUXE centre, you will have to drop everything and make yourself available,” the job description says.

The roles include response managers and situation managers to deal with the fallout of a no-deal exit, and staff will be required to “see through the fog”.

The advertisement on the website describes the emergency centre as “managing any situations that arise if the UK leaves the European Union without a deal”.

There are also vacancies for staff to liaise with the government’s crisis headquarters , the Civil Contingencies Secretariat (CCS).

The job description for the operations centre manager says the role is about “taking the lead … in a response to an emergency situation” and that the candidate “will have to react quickly to obtain the facts and delegate the immediate and next-day agenda”.

It was reported earlier this week that the Cabinet Office was recruiting another 50 staff for the CCS, which handles major disasters such as terrorist attacks, floods and disease epidemics.

The job advert for those roles, first reported by the Financial Times, said: “It is anticipated that the pool might be drawn upon from the middle of February 2019. Those selected will be asked to support until at least late June 2019 [although this may be extended].”

Some opponents of no deal briefed overnight that Theresa May’s success against hard-Brexit opponents in her party showed how limited the support was for leaving on WTO terms, but one source said the result had been read in Whitehall as signalling that there was almost no chance of parliament passing the prime minister’s deal.

Cabinet ministers had been briefed to expect another alarming no-deal paper to discuss at the cabinet meeting this week, but that meeting was moved in order to allow May to fly to Berlin and Brussels on Tuesday for last-ditch negotiations, and then rescheduled again from Wednesday after May faced a no-confidence vote.

Appearing before the public administration and constitutional affairs committee, the Cabinet Office’s chief civil servant, John Manzoni, said the government had been preparing for the possibility of no deal, and was now “progressively ramping this up”.

Of the £2bn the Treasury has allocated for doing so, about half had been distributed, he said. To prepare for no deal, 10,000 people had been hired, 5,000 more new jobs were in the pipeline and 5,000 more staff would be recruited if it happened.

The government had already set up “various arm’s-length bodies” to take on powers repatriated immediately from the EU if there was no deal, Manzoni said.

“All of that is taking place and now we are moving to the next phase, which is, if you like, what I would call operational preparedness,” he said.

Mark Sedwill, the cabinet secretary and head of the of the civil service, told MPs on the committee that the government was prepared for no deal, but was aware the process would be affected by external factors.

“Government is in pretty good shape, but of course the big dependencies are outside,” he said. “It’s about the private sector in this country, but it’s also about, in the circumstances, what arrangements can we agree with our EU partners?”

A written parliamentary question last month by the Green MP Caroline Lucas discovered that since the Brexit referendum 937 Environment Agency staff had been moved to work in Defra, almost 10% of the agency’s workforce.

Lucas said moving so many staff away from frontline protection efforts was “putting our most precious wildlife, beautiful landscapes and the basic safety of our air and water at serious risk”.