The Land Development Agency is being hindered by the fact that it is not clear exactly which land is State-owned.

That's according to Tom Philips, adjunct associate professor in the School of Architecture at UCD.

He was speaking as ministers are concerned over what they consider a lack of urgency to transfer State-owned land to the LDA.

The body is designed to look at State land and bring it forward for housing development.

There are plans to build 15,000 new homes on State property over the coming years to deal with the housing crisis.

But Prof Philips told Newstalk Breakfast it is facing some big hurdles.

"One of the issues is that we actually, in the supply and demand delivery equation that you have to bring housing forward, is to understand what land is available.

"There isn't central repository that is one place you can go and say 'That's all the State land'.

An apartment development under construction in Dublin. Picture by: Sam Boal/RollingNews

"So some of the land, they're actually having to work out what is actually State-owned land.

"That's a very slow process, but it's one that needs to be given the resources to happen very quickly.

"So it's actually to understand what the land is in the first place , before you can go and talk to the various parties that might be able to help to deliver it".

And he says while moves are happening, it is moving too slowly.

"The development process takes a long to get sites, so people get frustrated [that] they don't see activity on the ground.

"But that doesn't mean that there isn't a lot of movement below the surface of the water.

"There's a lot happening on it, but it just needs to happen quicker.

"And we need a minister to grab the bull by the horns and say 'We need one central repository of knowledge'.

"And say 'We have to get all these lands identified' - and then if anyone's got an impediment: What's the problem? What's the solution? What's the justification?'".

In a statement to Newstalk, the LDA said:

"There is no question of the LDA being hindered in its work by it not being clear what land is State-owned. In fact the LDA has developed a State Land Database available here.

"This is a comprehensive, live, interactive WebMap showing State-owned lands... Therefore the central repository that Professor Philips is seeking has been developed and is available on LDA website, and is one of the many projects the LDA has progressed since its foundation."