Just a fraction of the undeveloped land owned by Dublin's local authorities has been included on the new vacant sites register designed to crack down on land-hoarding in the city.

Land owners are subject to a 3% levy on the land value, which will be payable annually from next year.

However, the four local authorities in Dublin have included just 6% of the total council-owned land that is zoned and serviced for residential development.

Dublin City Council accounts for the vast majority of the sites listed.

As a result the local authority is set to fine itself more than €2 million.

It has included 21 sites on the register with an estimated capacity to build up to 1,900 new homes.

The Dublin City Council land, valued at more than €60m, is in locations including Ballymun, Inchicore and the city centre.

The former Readymix site in East Wall was originally bought by the Dublin Docklands Development Authority in 2006 and has remained undeveloped for more than a decade.

Independent Councillor and Lord Mayor of Dublin, Nial Ring, who lives in East Wall, says the site, which is now owned by Dublin City Council, is an example of an untapped housing resource.

"The people in the area would love to see something on it. I know there is a plan to use part of the site for the North Strand Fire Station extension, but it is a lovely site, right overlooking the Tolka River. What a gem we have and we are not using it."

Mr Ring estimates that €700m of capital investment would be required to develop all the sites that the council has included on the vacant site register.

"The Government has said there is money available for housing but unfortunately no-one seems to be writing the cheques."

A statement from the Department of Housing said that each local authority must consider the proposed use of sites in their ownership on the vacant site register, "such as selling the sites for development or undertaking local authority-own development".

The department said councils should "engage with the department for funding as appropriate".

Asked how much funding was provided for capital housing investment this year and next, the department said there was no precise amount of funding notified to individual local authorities in a particular year.

"The department provides the relevant funding to local authorities as social housing projects are advanced and the provision of appropriate capital funding will not be an obstacle to delivery."

Many of the sites that Dublin City Council has included on the list are former flat complexes, which the council plans to redevelop such as O'Devaney Gardens and Dominick Street.

Across the three other local authorities in Dublin, just one council-owned site is listed as a vacant site.

Dún Laoghaire-Rathdown has included land it owns in Ballyogan.

Fingal and South Dublin have not included any of the sites they own in the vacant site register.

Around 18.5 hectares of council land has been included from a total of 304 hectares across the city.

Architect and housing policy analyst Mel Reynolds said the figures show the potential to make a "significant dent" in the homeless emergency if funding is provided to the councils to build on the vacant sites.

However, Mr Reynolds warned that the low level of local authority sites on the register sends a worrying signal to private developers.

"If local authorities are either actively looking at loopholes to try and exclude land or if they are under-declaring their land, it doesn't bode well for anyone in the private sector taking this seriously.

"It is disappointing that the local authorities are taking so long to get moving on this. I think this is across all county councils and it looks to be systemic."

In a statement, Fingal County Council said it had identified one piece of land that was considered for inclusion on the register, but it was not entered "having regard to infrastructural requirements associated with the development of the site".

All of the local authorities said that the determination of sites for entry on the register has not concluded and further sites could be added.