THE British government must lay out its criteria for holding a border poll, a civic nationalism group has said.
Gerry Carlile, chief executive of Ireland's Future, said it was "undemocratic" for the government not to make clear its conditions for holding a unity vote.
According to the Good Friday Agreement, the Secretary of State "shall" call a poll "if at any time it appears likely to him that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland".
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However, Mr Carlile said it remains unclear how the Secretary of State is assessing public opinion.
He said voting patterns, particularly last year's general election, suggested greater support for Irish unity than recent opinion polls.
A poll in the Sunday Times at the weekend found that 42% of respondents were in favour of a united Ireland, with a further 11% undecided
"The polls that seriously matter are the elections," Mr Carlile said.
"The reality is we have nine pro-united Ireland MPs and we have eight pro-United Kingdom MPs. Should that be part of the criteria? Very possibly."
He added: "If you look at the polling, the Alliance and the Green voters seem to be united Ireland-leaning."
Mr Carlile said lack of clarity on the conditions for a poll was causing confusion.
"What should happen, in our view, is that the British government and the Irish government should liaise with the assembly and they should decide collectively, which is obviously the essence of the Good Friday Agreement.
"They should collectively decide what the criteria is because no-one likes uncertainty."
Alliance MP Stephen Farry said talk of criteria was "somewhat premature".
"I can understand people's desire to see criteria being set out but I think that is a secondary consideration at this stage," he told The Irish News.
"Obviously we are in a very fluid situation and there are a whole range of conversations happening before anyone contemplates either a border poll or the criteria for calling a border poll."
When asked about calls for a border poll, a British government spokesman said: "We remain fully committed to the Belfast (Good Friday) Agreement, which sets out the circumstances that would require a border poll to be called. We will continue to monitor the full range of evidence in this regard."
It is two years today since Ireland's Future held its first major conference in Belfast.
Mr Carlile said he felt the group had "encouraged the conversation (around Irish unity) and we have facilitated the conversation".
He said political events, particularly the impact of Brexit, had made the public think more deeply about Northern Ireland's constitutional position.
"I think people are now looking at this and thinking is there a better way forward?" he said.
"What can we create? Instead of living in this half-in, half-out of the EU on a divided island, is there a better future? Is there a better way for us?
"I think a lot of people who never thought they would ask that question are now asking it."
Ireland's Future is to hold an online panel tonight which will reflect on the last two years and conversations around Irish unity.
It will be broadcast on the group's Facebook, YouTube, Twitter and Instagram channels from 7pm.
