Planning for a potential Irish unity referendum can happen while working on the restoration of the Stormont executive, the leader of Sinn Féin has said.

The party’s president Mary Lou McDonald said that the “engagement and planning” for a border poll could be done alongside the return of the assembly.

Sinn Féin became the largest party in local government in the North at last week’s council elections, following on from the 2022 Assembly election where the party became the largest at Stormont.

The Northern Ireland Assembly has not been operational for more than a year due to the DUP’s ongoing boycott of powersharing institutions as a protest against post-Brexit trading arrangements.

Ms McDonald responded to Taoiseach Leo Varadkar’s assessment that a border poll would be “counterproductive” and the restoration of the Assembly should be prioritised.

The Sinn Féin leader said Mr Varadkar was “on the wrong page”.

“We know full well that we need the executive back up and running, we need a functioning assembly, we need the east-west institutions to work, we need the North-South piece to work as well,” she told the BBC.

“And you can do all of those things and at the same time have the kinds of engagement and the planning that I’m describing.

“The political system and political leaders have to have the capacity to multitask and do several things, several important, critical things at the same time.

“So I think to advance an argument that we will not prepare for the medium and long-term future simply because we have challenges in the present, that doesn’t stack up. That’s not responsible politics in my view.”

Ms McDonald also said that, as a result of budgetary pressures, the assembly should return before autumn.

“And yet, we’re hearing nonsense from people suggesting that perhaps we might have an executive back up and running in the autumn time. That to me is utterly farcical and completely unacceptable,” she said.

While the DUP were overtaken by Sinn Féin as the largest party at last week’s council election, the party maintained the number of seats it achieved in 2019, with 122 councillors.

In a statement to party supporters, DUP leader Jeffrey Donaldson said the results of the election reaffirmed their mandate to continue boycotting Stormont.

“The people who voted last Thursday have renewed our mandate to finish the job and lay the necessary solid foundations for a return of local accountable government at Stormont,” he said.

Mr Donaldson said “more work” was required by the UK government if the party was to return to the Assembly.

“We want to see the restoration of the Assembly and Executive on a stable and sustainable basis and primarily, that means addressing and resolving the problems created by the protocol and the economic and democratic deficit that it has created for Northern Ireland and its people,” he said.

The DUP opposed the protocol as the party believed it created a border in the Irish Sea.

The Windsor Framework was British prime minister Rishi Sunak’s plan to tackle the problems the DUP had with the protocol by minimising checks on goods coming from mainland UK to Northern Ireland.

Mr Donaldson said the Windsor Framework “does not deal with some of the fundamental problems at the heart of our current difficulties”.