Tory deal with DUP raises concerns in Dublin over Good Friday agreement and absence of ‘nationalist voice at Westminster’ • General election 2017 - live updates

The Democratic Unionists’ deal to shore up a minority Conservative government will be sealed this week with the emphasis on an economic aid package for Northern Ireland and an assurance of no referendum on Irish unity.

Ten DUP MPs are likely to help Theresa May form a new administration on a “confidence and supply” basis , in return for demanding extra financial support for Ulster farmers to help them cope with the abolition of common agricultural policy support once the UK leaves the EU.

But the looming prospect of an understanding between the two parties raised concern in Dublin, with the outgoing taoiseach, Enda Kenney, stressing the importance of maintaining the Good Friday agreement and warning against the absence of a “nationalist voice at Westminster”.

DUP sources said that while they would seek a promise from the new government that there will be no border poll on Irish unity and no “hard frontier” on the island of Ireland after Brexit, the majority of the party’s demands will centre on aiding the local economy.

The same sources stressed that the DUP had no interest in including controversial social issues such as gay marriage or abortion in any deal.

From climate denial to abortion: six DUP stances you should know about Read more

While the DUP has vetoed moves in the Northern Ireland assembly to bring in gay marriage equality as well as reform the region’s strict anti-abortion laws, the party sources said these controversies “were not and will not be raised” by their negotiators in talks with the Conservatives.

In her first television interview since the DUP won 10 seats at the general election, the party’s leader, Arlene Foster, said “discussions continue but we have made good progress”.

On the package the DUP will seek from a minority Tory government, Foster said: “I am not going to negotiate over the airwaves. But we will act in the national interest and do what is right for the United Kingdom as a whole and in particular for Northern Ireland.

“There has been a lot of hyperbole since Thursday. A lot of things said, a lot by people who really don’t know what we stand for. Just to be clear, we will act in the national interest, we want to do what is right for the whole of the UK, we want to bring stability to the government of the United Kingdom.”

She is scheduled to meet Theresa May at Downing Street on Tuesday when it is expected the DUP-Conservative deal should be secured.

While Foster has kept her counsel about the details of the deal the DUP is looking for, party sources have told the Guardian that assurances on no border poll, no new post-Brexit security checks on Northern Irish citizens coming into Britain and a soft border on the island of Ireland remain the foundations of the ”constitutional” side of the arrangement.

On the socioeconomic side, the DUP will seek special aid for Ulster farmers to replace the CAP subsidies that will be lost once the UK leaves the EU, a 50% cut or even the total abolition of airport passenger duty tax for Northern Ireland’s airports and a major extra capital spending programme from the Treasury for the region mainly focused on hospitals and schools.

As well as the aid package and political reassurances, the DUP may get some of its senior figures elevated to the House of Lords. The Guardian has learned that among these is former DUP leader and ex-first minister Peter Robinson, who is credited inside the party with running a highly successfully election campaign behind closed doors.

Regarded by the DUP rank and file as the party’s “brain”, DUP negotiators want Robinson at Westminster to help their MPs keep the arrangement with the Conservatives up and running over the next few months.

The arrangement will be run on a “confidence and supply” basis remarkably similar to the one that Ireland’s main opposition party, Fianna Fáil, operates in the Dáil. Fianna Fáil offers up support in no confidence votes and backs a budget for the minority Fine Gael/independents coalition in Dublin. That arrangement, DUP sources stressed on Sunday, has kept the Irish coalition in power for almost 18 months.

'Confidence and supply': what does it mean and how will it work for the new government? Read more

The Irish government, meanwhile, issued a warning that any Conservative-DUP deal should not undermine the talks process aimed at restoring devolved power-sharing government in Northern Ireland.

In one of his last acts before leaving office this week, Ireland’s prime minister, Enda Kenny, has expressed concern over the DUP-Conservative deal at Westminster. The taoiseach had a telephone conversation with May on Sunday, a government spokesman said in Dublin.

“The Taoiseach indicated his concern that nothing should happen to put the Good Friday agreement at risk and the challenge that this agreement [with the DUP] will bring”, a government statement said.

Facebook Twitter Pinterest The Irish taoiseach, Enda Kenny, telephoned Theresa May to express his concern over the DUP-Conservative deal. Photograph: Niall Carson/PA

The statement also said that both leaders “agreed that of immediate concern were efforts to establish an executive as soon as possible, with exploratory discussions with the Northern Ireland parties to take place tomorrow”.

A Downing Street spokesperson said: “The prime minister reiterated that the government’s approach and objectives in the forthcoming talks to re-establish the Northern Ireland Executive remained unchanged.

“The two leaders spoke about their willingness to continue close cooperation as the UK embarks on leaving the European Union, with no return to a hard border.”

The Irish foreign minister, Charlie Flanagan, is scheduled to travel to Belfast on Monday to co-host talks with the main parties represented in the Stormont assembly.

Ahead of his visit north, Flanagan pointed on Sunday to a key clause in the 1998 Good Friday agreement that states that both the London and Dublin governments must adhere to “rigorous impartiality” when it comes to dealing with all sides of the Northern Ireland political divide.

Exploratory talks will resume in Belfast on Monday with Sinn Féin and the DUP, the two dominant parties on whom the fate of power sharing rests.

There are serious concerns in Dublin that a Tory-DUP national deal would undermine the neutrality of the co-chair of the Belfast talks, the Northern Ireland secretary, James Brokenshire.

Sinn Féin criticised the decision by the DUP to consider propping up a minority Conservative government that they said “betrayed the interests of the people”. The party said the arrangement would “end in tears”.

Critically, however, so far Sinn Féin has not pulled out of the devolution talks in response to the looming Tory-DUP deal.