PEACE centre plans at the former Maze prison site have been dropped by the project's development board, the UUP has claimed.
It emerges after a near six-year spat between the DUP and Sinn Féin stalling the site's proposed multi-million-pound redevelopment.
In 2013, then DUP leader and first minister Peter Robinson halted the peace centre plans after unionist critics argued it would become a shrine to terrorism.
Sinn Féin's Martin McGuinness, then deputy first minister, responded by saying no further development would take place until the issue was resolved.
Since then most requests to use or visit the site have not been approved because of the ongoing row. Stormont officials have mostly maintained this block on requests since the executive's collapse in 2017.
The Maze/Long Kesh (MLK) prison was the site of the IRA hunger strikes and held some of the north's most notorious paramilitaries before it closed in 2000.
A UUP delegation including European election candidate Danny Kennedy met with representatives of the Maze Long Kesh Development Corporation (MLKDC), the body in charge of the site outside Lisburn.
The Ulster Unionists said they were briefed on the revised strategy, and the peace centre has been dropped from the proposals.
Read More: 2013 - Peace centre will be built says architect
Mr Kennedy welcomed the move, arguing that the peace centre was a "toxic idea for thousands of victims of terrorist violence".
He also said it was "an outrage that the corporation has been left without political direction for nearly six long years".
"The body charged with delivering a £300 million development, creating 5,000 jobs, is reduced to carrying out essential maintenance and health and safety work," Mr Kennedy said.
He added: "Properly developed, the Maze could be the catalyst for a £800m investment with 14,000 high quality jobs and several thousand new homes.
"I am asking my MLA colleagues to ensure the delivery of this site with the associated prosperity is on the agenda for the current political talks."
In its latest annual report for 2017-18, MLKDC noted how the peace centre project was "put on hold in 2013-14 and planning permission lapsed in May 2018".
Sinn Féin MLA Gerry Kelly said the DUP had "bowed to pressure from other unionist parties" several years ago not to develop the site.
"Now just two days into a talks process Danny Kennedy and the UUP seemed interested only in welcoming a decision to renege on yet what was another agreement and a Programme for Government commitment," he said.
He added: "The buildings which remain on the Long Kesh site are listed and will be part of the development of the rest of the site."
DUP Lagan Valley MP Jeffrey Donaldson said his party supported development of the Maze as a "shared space".
"The behaviour of republicans however meant there could be no consensus and the development of a peace centre would actually be a source of division," he said.
An Executive Office spokeswoman said: "Any decision regarding the future development of the Maze/Long Kesh site would be a matter for ministers. No decisions have been taken."
