BELFAST (Reuters) - After years of tumultuous ties with Conservative governments, Northern Ireland leaders are hoping for a very different era if Labour take power this week, with everything from post-Brexit trade to a soldiers' amnesty potentially up for renegotiation.

    Some Irish nationalists hope the expected Labour victory in Thursday's parliamentary election will also create space to press their case for a United Ireland.

    But like their pro-British rivals, top of their wish-list will be a reversal of what they say has been chronic under-funding of one of the United Kingdom's poorest regions.

The list of demands give a flavour of the scale of the challenge awaiting leader Keir Starmer if his opposition Labour Party is elected, and the potential to improve some ties in Belfast, and in Dublin, after years of strain.

"There are so many levels at which the current government has failed Northern Ireland, it would be hard to summarise them all in one answer," the leader of the cross-community Alliance Party Naomi Long said at her party's manifesto launch.

    "I hope we will see a change of government to one which actually respects the Good Friday Agreement ... rather than acting as a wrecking ball to it," she said, referring to the 1998 peace deal between those seeking a united Ireland and those wanting to remain part of the United Kingdom.

The Conservatives plunged Northern Ireland into a political crisis when the United Kingdom as a whole backed its vote to leave the European Union in 2016, threatening nationalists' cherished open border with EU member Ireland and, later, unionists' ties to the rest of Britain.

It took almost eight years and five Conservative leaders before Rishi Sunak restored a semblance of calm with a deal on post-Brexit trade rules, enabling February's restoration of Northern Ireland's government after a two-year unionist boycott.

Despite that, unionists will likely push the next government to further ease the remaining trade frictions that many supporters see as a threat to their British identity.

    Also in the in-tray is one of the most contentious issues - a proposed amnesty for ex-soldiers and militants involved in Northern Ireland's decades of violence.

Sunak alienated parties across the spectrum by pushing ahead with the amnesty, once again straining relations with the Irish government in Dublin, which has mounted a legal challenge. Labour has promised to scrap it.

UNITED IRELAND

The UK's exit from the European Union, which 56% of Northern Irish voters opposed, led to increased calls for a referendum on a united Ireland.

Under the 1998 deal that ended 30 years of nationalist-unionist bloodshed, a referendum is at the discretion of the British government.

Opinion polls consistently show a clear majority in favour of remaining part of the UK, although nationalists hope changing demographic trends favour their cause.

While Labour have historically been seen as sympathetic to nationalists, unionists are putting faith in Stamer's promise to defend the union.

"There are many who sometimes casually suggest that Labour is in some way pro nationalist, pro Irish nationalism," said Gavin Robinson, leader of the Democratic Unionist Party (DUP), the largest pro-British party.

    "That is not true of this Labour party."

The second largest unionist party, which unlike the DUP opposed Brexit, believes Labour cannot be worse than the Conservatives.

    "Under the Conservative government, the cohesion of the United Kingdom has dissipated," said UUP leader Doug Beattie, who vowed to work with Labour to reverse that.

Sinn Fein, the largest nationalist party, is hoping that a strong performance in the elections this week, likely at the expense of the struggling DUP, will further boost its campaign to end British rule.

Already the largest party in the devolved assembly, the party could cross off another milestone if, as expected, it takes over as the region's largest party in Westminster, despite its long-standing policy of not taking up its seats there.

    "Labour have claimed the Good Friday Agreement as part of one of their biggest successes so therefore you'd like to think that they're going to bring a totally different approach to the Tories" on a possible referendum, Sinn Fein's Michelle O'Neill, Northern Ireland's first minister, told Reuters.

However Jon Tonge, Professor of Politics at the University of Liverpool, said that could be wishful thinking, noting that Starmer said last year that a vote on removing the frontier between Northern Ireland and Ireland was "not even on the horizon".

(Reporting by Amanda Ferguson; Writing by Padraic Halpin; Additional reporting by Conor Humphries; editing by Philippa Fletcher)

By Amanda Ferguson