There are "vast amounts" of land available to tackle the housing crisis, a housing conference has heard.

The conference was organised by the Raise the Roof group, which includes the Irish Congress of Trade Unions and homeless groups, and is campaigning for housing to be made a constitutional or legislative right.

Architect Mel Reynolds told the event in Dublin that half of all residential-zoned land in Dublin is State controlled, either being owned by a local authority or NAMA.

He said this would be enough to provide 71,000 new homes.

But he said increased supply had not led to lower house prices in the past and private housing is currently out of reach for low and middle-income earners.

According to CSO figures on wages, he said, the maximum price for an affordable house is €245,000 but the average price paid by a first-time buyer in Dublin was €370,000.

However he said the Ó Cualann Co-operative Building Association was able build three-bedroom houses in Ballymun for €219,000 by being able to use State land.

Chief Executive of the Housing Agency John O’Connor said the focus of public housing should be on providing rental living that people can afford.

He said the makeup of households has changed - while 91% of private houses were owner-occupied in 1991, it had fallen to 78% in 2016 and 59% in urban areas and 56% of households now consist of one or two people - 75% are three or fewer.

Deputy Chief Executive of Dublin City Council Brendan Kenny said public housing as a concept "is the way to go".

But he said the council does not have the land available to build large local authority estates like it did 20 or 30 years ago,

Mr Kenny said the amount of land actually owned by Dublin City Council is 120 hectares and 95 hectares is already in the construction pipeline.

The other 25 hectares is in Ballymun, Cherrywood and Darndale already have a high concentration of social housing.

He said that part of the problem is objections from existing communities to small-scale social housing developments.

However, Professor Tony Fahey from UCD said that public housing in Ireland should be seen as a success and not as a mistake based in 4% of the estates.

He pointed to west Tallaght as a recent example of a successful local authority estate that developed a social mix over time.

Mr O’Connor said public housing should be opened up to more people and pointed out that other countries do not have income limits.

Rebecca Keatinge of the Mercy Law Resource Centre said a right to housing is recognised either constitutionally or legislatively by many European countries including Belgium, Greece, Finland,Portugal, Sweden and Scotland.