Pro-Ireland party Sinn Fein won the largest number of local council seats in Northern Ireland on Saturday, outstripping pro-UK unionist rivals in a historic first for the province.

By a wide margin of gains, the party supplanted the Democratic Unionist Party (DUP) as the dominant force in local government in the region created just over 100 years ago to ensure a pro-UK majority.

Sinn Fein, the former political wing of the paramilitary IRA, had won 143 of 462 seats across Northern Ireland's 11 local councils with just six seats left to declare.

For 15 months, the DUP has boycotted Northern Ireland's devolved government over its opposition to post-Brexit trade arrangements, paralysing its power-sharing institutions at Stormont.

Sinn Fein leader Michelle O'Neill called the result "momentous", telling the BBC her party's campaign had "resonated with the electorate".

The strong showing by Sinn Fein follows its unprecedented win in elections to Stormont one year ago where it also replaced the DUP as the biggest party in the assembly.

The recent campaign over local services like waste collection and leisure services was dominated by the question of whether the DUP would return to the executive.

O'Neill said in the wake of the election result, Sinn Fein would "double down in terms of getting an executive restored".

Earlier, she called on the British and Irish governments to "get engaged" and create "a plan now for a way back to a restored executive."

DUP leader Jeffrey Donaldson defended his party's result saying its vote had "held up well".

With the last seats left to declare, the pro-UK party had secured 122 seats, equalling its numbers in the last local elections in 2019.

Donaldson attributed Sinn Fein's success to the "collapse" of its nationalist, pro-Ireland rival, the Democratic Social and Labour Party (SDLP).

In February last year, the DUP withdrew from the devolved government at Stormont in opposition to the so-called Northern Ireland Protocol.

It has argued that new trading rules after Britain's departure from the European Union drive a wedge between the Northern Ireland and the rest of the UK.

The DUP also claims the protocol, which keeps Northern Ireland under EU trade rules and creates a defacto trade border in the Irish Sea, makes Sinn Fein's goal of a unified Ireland more likely.

Parts of the protocol have been renegotiated into the Windsor Framework to ease trading bottlenecks with the rest of the UK.

But the DUP has refused to return to government in spite of the changes, with its boycott fuelling political uncertainty in Northern Ireland, where 30 years of violence over British rule only ended in 1998.