Campaigners fighting for full restoration of the last buildings used by the 1916 Rising leaders are to picket the site after protesters occupied it.
About 30 people made their way into 14-17 Moore Street in Dublin on Thursday evening after hoardings went up to allow preparations for construction and redevelopment at the site.
The Government bought the buildings last year as part of a four million euro restoration plan, which includes No 16 where the rebel leaders held their last council of war.
Among those who took part in the occupation is a grandson of The O’Rahilly, Proinsias O’Rathaille.
Campaigners have warned development of surrounding lands into a shopping centre will destroy the integrity of the historically important site, including No 18 which will be knocked down to make room for an entrance to a museum and potentially No 10 where the rebels took refuge as British forces overran the GPO.
Barry Lyons, honorary secretary of the the 1916 Relatives Association, said they felt as though they had been deceived by Government despite assurances last year that they would be fully consulted and briefed on plans.
“We are fully supporting the occupation, and encouraging it,” he said.
“When we were dealing with Minister for Arts, Heritage and the Gaeltacht Heather Humphreys we felt as though we were deceived by what we were told,” he said.
“We were told nothing would go ahead without us being informed or without our consultation but the deal was signed off before our last meeting. While the minister was at a photocall to announce it, we were in Kildare Street being told about it.
“They are going ahead with demolition.”
The Save Moore Street group have called on supporters to picket the site at lunchtime to fight what they say is a “demolition of history”.
The Government plans are to restore the fronts of 14-17 Moore Street and open a commemorative centre and museum.
Concerns remain over what will be allowed on the wider battlefield site at the back of the GPO where developers have been attempting to build a large shopping complex for years.
The buildings on Moore Street were owned by Chartered Land which had planned a retail centre covering 2.7 hectares from the old Carlton cinema on O’Connell Street to Moore Street.
The restoration is one project in the Government’s plans for the centenary, which also involves 22 million euro being spent on other projects by next Easter to create permanent reminders of the 100-year anniversary.
No 16 Moore Street was the location where the decision was taken to surrender on Saturday April 29, 1916.
It was declared a national monument in 2007 and an option had been put on the table to allow the developers to build the shopping centre with a commitment to creating a museum or interpretive centre at the site.