The Irish government has expressed alarm at Boris Johnson’s approach to Brexit as tension begins to mount over the increased risk of no deal.

Michael Creed, Ireland’s agriculture minister, said the new position of the British government, which involves demands for a new deal without the Irish border backstop within 98 days, was a concern.

“The makeup of this government seems to be a mirror image of his [Johnson’s] own viewpoint substantially and obviously that would be of concern to us,” he told RTÉ radio.

“What the government is concerned about now is the approach of new administration in the UK to the withdrawal agreement. We see that as the way to have a planned withdrawal arrangement and obviously what we are hearing from the government is quite alarming.”

On Wednesday the Irish taoiseach, Leo Varadkar, said a “whole new” Brexit deal was “not going to happen”.

No details have yet emerged of Johnson’s alternative proposals for the Irish border but he distanced himself from speculation about a return to a Northern Ireland-only backstop, telling the House of Commons that no part of the UK would remain in the customs union or single market.

At the same time he referred to “abundant facilitations already available” away from the border for checks that could seal a deal. This could be read as an attempt to cherry-pick elements of the backstop arrangements, which include proposals for limited checks in warehouses, on farms and at ports and airports to ensure the single market was protected.

Officials and politicians on both sides of the border welcomed the appointment of the former chief whip Julian Smith as Northern Ireland secretary. Smith is expected to fly to Belfast on Friday for his first series of meetings. His in-tray includes keeping the DUP onside for Brexit, getting devolved government restored and ensuring the region’s businesses, police and communities are ready for no deal.

It is understood the Democratic Unionist party is happy that a “heavyweight” and a man it is familiar with will be in charge after Karen Bradley, who survived several calls to resign over various gaffes during her tenure.

Nigel Dodds, the head of the DUP in the Commons, called on Johnson to “strain every sinew to strengthen the union, get a deal to leave on the right terms and get Stormont up and running again”.

The DUP’s arrangement with the Tories holds for the duration of the government but must be reviewed before every Queen’s speech, which has been delayed by the Tory leadership battle. The party is expected to stress the urgent need to get government going again in Northern Ireland.

Last week analysis from Stormont’s department for the economy said a no-deal Brexit could put 40,000 jobs at risk in Northern Ireland.

The Freight Transport Association (FTA) and other business interests including Retail Consortium of Northern Ireland will be seeking early meetings with Smith’s team to drive home the realities of the all-island economy.

Seamus Leheny, head of the FTA in Northern Ireland, said: “We have members who cross the border to distributions centres outside Dublin with 45-minute windows. If there are any delays at the border and they lose the slot they go to back of the queue. We are not against Brexit or optimism. What we are interested in is the facts.”