The Democratic Unionist Party (DUP) has confirmed that it will block the election of a new speaker at the Stormont Assembly in a move that will prevent the return of power-sharing in Northern Ireland. 

The DUP had previously announced that it would not be electing a deputy first minister after Sinn Féin became the first nationalist party in history to win the most seats in a Northern Irish election that was held on May 5.

The move, which was partly undertaken as a protest against the Northern Ireland Protocol, prevents the forming of a new Stormont Executive. 

Under the rules of the devolved power-sharing administration in Northern Ireland, a first minister cannot be in power if there is no deputy first minister or vice versa. 

Unionists oppose the Northern Ireland Protocol because it creates a defacto trade border down the Irish Sea. The protocol was agreed upon in 2019 during the Brexit Withdrawal Agreement to prevent the return of a hard border on the island of Ireland. 

DUP leader Sir Jeffrey Donaldson said on Friday that he was sending a "clear message" to the European Union and the British Government by refusing to nominate a speaker at the Stormont Assembly. 

Speaking shortly before the first plenary session of the new assembly, Donaldson said the issue of the Northern Ireland Protocol needed to be urgently addressed. 

"Because of the harm it is doing, undermining political stability, damaging the agreements that have formed the basis of political progress made in Northern Ireland, to our economy, contributing to the cost-of-living crisis, this matter needs to be dealt with," Donaldson said. 

Sinn Féin Vice President Michelle O'Neill described the move as "disgraceful" and accused the DUP of attempting to "deny democracy". 

"This is our hour of decision, not tomorrow, and not for a moment longer can the DUP deny democracy, punish the public, boycott this Assembly and executive, and prevent us from putting money in people's pockets," O'Neill said. 

"Every one party in this chamber told the electorate that they would turn up on day one. Well, the DUP have failed on day one." 

Taoiseach Micheál Martin described the DUP move as "unsatisfactory" and said issues surrounding the Northern Ireland Protocol should not thwart a return to power-sharing. 

"The people elected an Assembly, the Assembly should meet, and then the Assembly should form an executive," Martin told reporters in Kildare. 

"Yes there are issues that unionism has raised with us in respect of the protocol, but those issues should not prevent the establishment and convening of the Assembly and the formation of the executive." 

The Taoiseach said current evidence suggests that the Northern Ireland Protocol is having a positive economic impact on the region. 

The 90 MLAs who were elected in last week's historic election met for the first time at the Stormont chamber on Friday. 

All 90 MLAs were required to sign the register and designate as nationalist, unionist, or other. 

Donaldson, who was elected as an MLA for Lagan Valley last week, was not present in the Stormont chamber on Friday because he has chosen to retain his position as an MP in Westminster. 

Instead, former DUP MP Emma Little-Pengelly will replace the party leader on the Stormont benches.