Sinn Fein, an Irish nationalist party in Ireland, celebrated a historic first-ever win in elections for Nothern Ireland - however, pro-UK unionists are threatening to boycott the elected government.

Sinn Fein, the revolutionary IRA's political wing, secured 21 seats for the 90-seat legislature, which lead to a victory.

On Thursday, England, Wales, and Scotland voted in regional elections - the population bashed down British Prime Minister Boris Johnson's Conservative party, but without a landslide win for Labour.

On Tuesday, Johnson is expected to present his post-election plans in the parliament during the Queen's Speech - the address will have to deal with the sensitive issue of Northern Ireland, which has been drenched in sectarian strife for years.

Sinn Fein has been fighting for a referendum to reunify Ireland with Northern Ireland after the north was created as a Protestant territory. Sinn Fein eyes 28 seats to gain the seat of first minister for Sinn Fein leader Michelle O'Neill.

The Unionists have taken the role of the first minister in the Stormont assembly before collapsing in protest at post-Brexit trading policies between the UK and EU.

Unionists warn of a 'divisive' Irish unity referendum

On Monday, the leader of North Ireland's Democratic Unionist Party (DUP), Jeffrey Donaldson, warned against a referendum on Irish unity, which he called "divisive".

Pro-Irish nationalists Sinn Fein are expected to become the largest party in Northern Ireland's regional assembly, with voters heading to the ballot box.

Sinn Fein's win could enable the former political wing of the paramilitary IRA (Irish Republican Army) to lead a power-sharing government for the first time.

Pro-UK unionists, like the DUP, have held power for over a century since Northern Ireland was created. The unionists are arguing that Sinn Fein will use power to push for a referendum on re-joining the Republic of Ireland, its neighbor to the south.

"Sinn Fein wants to work in alliance with dissident republicans, people who are continuing to engage in violence, people who have committed murders on our streets in Northern Ireland," DUP leader Jeffrey Donaldson said.