Sinn Féin has welcomed the appointment of Drew Harris as Garda Commissioner and pledged to hold him to account in his new role.
The party has had a tense relationship with Mr Harris during his tenure as Deputy Chief Constable for the Police Service of Northern Ireland (PSNI).
Some within the party blamed Mr Harris for the arrest of Gerry Adams in connection with the abduction and disappearance by murder of Jean McConville.
Sinn Féin MLA Caitríona Ruane also withdrew from the Policing Board panel that would go on to select Mr Harris to the role within the PSNI, saying she believed the process may have been compromised.
Speaking after the appointment was made on Tuesday, the party’s spokesman on justice, Donnchadh Ó Laoghaire, said the party intended to work constructively with Mr Harris and would be seeking to meet him to discuss his priorities as commissioner.
Mr Ó Laoghaire said: "Sinn Féin has high standards for policing, and we will continue as we have done to date, to hold An Garda Síochána to account, and to pursue comprehensive reform of policing."
PSNI Chief Constable George Hamilton has also welcomed the appointment of his deputy – “a man of unfathomable strength, humility and grace” – to the role of Garda Commissioner.
"While there is no doubt that the Police Service of Northern Ireland will be a poorer place without his contribution, he will remain a colleague when he takes over the leadership of An Garda Síochána," Mr Hamilton said.
The Police Federation for Northern Ireland (PFNI) officers representation body described the appointment as “ground-breaking and historic”.
PFNI chair Mark Lindsay described Mr Harris as “an outstanding police officer”.
“His grasp of the wide range of issues affecting policing in both jurisdictions means that Mr Harris comes well prepared for the challenges ahead,” he said.
“Brexit is already on the policing agenda in both Northern Ireland and the Republic of Ireland and the perspective he will bring to the dialogue will be invaluable.”
The British government Secretary of State for Northern Ireland, Karen Bradley, offered her congratulations.
“This is a critically important post and I am delighted that An Garda Síochána will be able to draw on Drew’s vast policing experience which is as broad as it is deep,” she said.
Former Alliance Party justice minister David Ford MLA said Mr Harris’s appointment was “well-deserved recognition of his achievements”.
Mr Ford said the new vacancy for a PSNI deputy chief constable “illustrates how vital it is to get a full Policing Board back in position”.
In the absence of Stormont he called on Ms Bradley to act as “the issue is now critical”.
SDLP policing and justice spokeswoman Dolores Kelly MLA described the appointment as “a remarkable personal achievement”.
“The timing of this appointment is critical, given that post-Brexit, North-South policing relations will be of utmost importance,” she said.