Sinn Féin has included Gerry Adams on its negotiating team to form the next Irish government, fuelling renewed scrutiny over the party’s links with the IRA.

A party briefing note leaked on Friday named Adams as a negotiator, raising questions as to why he was not on the published list. The disclosure came as political opponents piled pressure on Sinn Féin to renounce the IRA in advance of talks to form a coalition government.

On Thursday, Micheál Martin, the Fianna Fáil leader, accused the party of having supported a vicious sectarian murder campaign during the Troubles, and of still remaining under the sway of shadowy figures.

The Garda commissioner, Drew Harris, was drawn into the row on Friday when he confirmed that the Irish police agreed with a Police Service of Northern Ireland assessment that the Provisional IRA’s army council oversaw Sinn Féin and the remnants of the IRA.

The taoiseach, Leo Varadkar, challenged the Sinn Féin leader, Mary Lou McDonald, to respond. “Why doesn’t McDonald disband the army council [the IRA’s decision-making body] and the PIRA, or if she cannot, repudiate them and sever all links and do so publicly and unequivocally?” he tweeted.

The controversies put the republican party on the defensive two weeks after it won the popular vote in Ireland’s general election.

No party has an overall majority in the hung parliament, but Sinn Féin scored a symbolic victory on Thursday when McDonald won the most votes among the party leaders nominated for taoiseach. Varadkar resigned as head of government but will serve as caretaker leader until a new government is formed.

Sinn Féin’s election breakthrough came on its promise to build affordable housing, freeze rents and fix healthcare. However, Fianna Fáil and Varadkar’s ruling Fine Gael party have ruled out forming a government with Sinn Féin, citing policy differences and its IRA links.

Last week the party named a negotiating team of four TDs (MPs), with no mention of Adams, who stepped down as leader in 2018 and as a TD this month.

The leaked briefing paper named four other unelected officials as negotiators, including Martin Lynch, who was jailed in the 1980s for possessing a rocket launcher and other arms.

In a blogpost titled “The myth of shadowy figures”, Adams said the party had made no secret of its backroom advisers and strategists.

“Many have had long and fruitful relationships with senior Irish and British government ministers and officials as we have charted a course from conflict, through a peace process, to an end to conflict and peace,” he wrote.