Alliance leader Naomi Long has said that her party will "engage respectfully" in any conversations about Northern Ireland's future.

It comes after the tánaiste (Irish deputy prime minister) Simon Harris asked some political parties in Northern Ireland, including unionists, for feedback on Fine Gael's so-called "blueprint" on Irish unity.

The Ulster Unionist leader, Jon Burrows, called the plans "political suicide". Democratic Unionist Party (UUP) leader Gavin Robinson called it a "crass attempt to outbid Fine Gael's rivals in Dublin".

Long said Alliance would take part "without prejudice to how we might decide the constitutional question".

Speaking on Sunday Politics, Long said: "We're not there to be advocates for change or advocates for the status quo, but we will engage constructively."

She said Harris was also looking at how both parts of the island could work better together "even if there isn't unity", adding that Northern Ireland's financial challenges made that discussion necessary.

Among their proposals, Fine Gael has suggested appointing a junior minister in the Irish government for "north south relations".

The party also published a document by an economist who works as an adviser to Harris, where it was suggested that the first-year cost of reunification ranges from about €3bn (£2.5bn) to €25bn (£20.8) to the Irish exchequer.

In a letter accompanying the proposals, he said: "No one political party owns the discussion about the future of this island, nor should any one party seek to determine its outcome.

"That is why I believe this must be an inclusive conversation, informed by evidence, respectful of different constitutional perspectives and grounded firmly in the Good Friday Agreement and the principle of consent," he wrote.

"I am writing to all major political parties across this island - I hope you will receive this report in the constructive and respectful spirit in which it is intended," he wrote in the letter, seen by BBC News NI.

His proposals came days after the taoiseach (Irish prime minister), leader of Fianna Fáil, circulated a document to his parliamentary party laying out his thoughts on how to prepare for a united Ireland.

Robinson, DUP leader, said: "Simon Harris and the Irish Government can find time to write to unionists about breaking up the United Kingdom.

"They should find time to answer the ICRIR's (Independent Commission for Reconciliation and Information Recovery's) questions about the Irish Republic's role in Troubles' deaths."

He said if Harris "wants to build trust with unionists" he "can start by answering" letters sent to Dublin by Sir Declan Morgan, the ICRIR's chief commissioner and give the Omagh [bomb] families a public inquiry in the republic".

The SDLP leader, Claire Hanna, welcomed the letter and said: "A New Ireland must mean precisely that: an opportunity to build a new nation, not simply reverse partition".

"Crucially, that preparation must also deliver a better Northern Ireland along the way, with stronger public services, greater economic opportunity and better living standards for communities," she added.

Burrows, UUP leader, called Fine Gael's plans a "constitutional pet project" and said that his party "will not participate in any project designed to dismantle the United Kingdom".

"We have no interest in a republican invitation to commit political suicide."

He added that his party will work with everyone to promote prosperity: "We are willing partners in practical cooperation that benefits everyone. Simon Harris should focus on building trust and respecting our place in the union."