Arlene Foster says issues of trade are being derailed by government trying to use EU negotiations to promote united Ireland

The DUP leader, Arlene Foster, has accused the Irish government of hijacking the Brexit negotiations to promote a united Ireland.

Speaking before her party’s annual conference, Foster expressed her alarm at comments from the Irish foreign minister, Simon Coveney, who told a parliamentary committee he wanted to see a united Ireland in his political lifetime.

Foster told BBC Radio 4’s Today programme that such interventions were hampering efforts to move the stalled Brexit negotiations to discussions about trade.

She said: “The Irish government are actually using the negotiations in Europe to put forward their views on what they believe the island of Ireland should look like in the future.”

She added: “We’ve heard from the foreign minister of the Republic of Ireland just yesterday talking about his aspiration for a united Ireland. He is entitled to have that aspiration but he should not be using European Union negotiations to talk about those issues. What he should be talking about are trading relationships.”

Earlier this week, Foster accused Dublin of blackmail after Ireland’s taoiseach, Leo Varadkar, warned that the country would block progress in Brexit talks unless the UK came up with proposals to avoid a hard border with Northern Ireland.

In her Today interview, Foster refused to address Varadkar’s suggestion that the UK could continue to apply the rules of the customs unions and the single market without being members of the EU.

She said: “What we don’t want to see is any perception that Northern Ireland is in any way different from the rest of the United Kingdom, because that would cause us great difficulties in relation to trade. The single market that really matters to us is the single market of the United Kingdom.”

Foster claimed Ireland’s hard line on the border issue was preventing the talks moving on. “It is wrong that the Irish government … will not allow the process to move forward until they have certain things they demand. I have always felt it very difficult to have an agreement in relation to the border between Northern Ireland and the Republic, but we haven’t moved to the next stage to talk about trade.”

She added: “You can’t have it both ways. Leo Varadkar is saying he won’t allow the discussions to move to the next stage, to talk about trade, until he has had a commitment in relation to the Irish border. You cannot have it in that fashion. We want to move to the next stage.”

Foster also accused the US diplomat Richard Haass, who chaired political talks in the province in 2013, of bias after he claimed talks about returning power sharing to Northern Ireland were being hampered by the UK government being “wedded” to the DUP.

Foster, who has agreed to back the UK government in return for extra funding for Northern Ireland, said his comments were wrong. She added: “It shows that sometimes when independent people are brought in they are sometimes not very independent.”

Asked whether Haass was impartial, she replied: “No. Not at all.”

She claimed the DUP was committed and working towards the restoration of power sharing.

“Just because we exert a level of influence in London, it is not mutually exclusive to have an administration in Belfast. In fact, the two are complementary. That’s why we have been pushing to bring about devolution and will continue to do so,” Foster said.