Four years after plans for a proposed national children's hospital were rejected by An Bord Pleanála a new planning application has been lodged for approval.

The choice of site, this time at St James' Hospital in Dublin, remains divisive.

Minister for Health Leo Varadkar said today a huge amount of work had been done to get the planning detail right, and to ensure the facility could be completed by 2019.

The plans also include those for the two paediatric outpatient departments and urgent care satellite centres, at Tallaght and Connolly hospitals.

Speaking on RTÉ's Today with Keelin Shanley, Mr Varadkar said he was not taking anything for granted and emphasised that An Bord Pleanála was an independent body.

"What's different from last time is that a dedicated statutory board, the National Paediatric [Hospital] Development Board was established, with people on it who have a lot of experience with big projects like the Aviva and so on and they're the ones who've been very much behind this and driving this.

"But there have been what they call pre-planning discussions and that's where the development board go into An Bord Pleanála and has what they call a pre-planning discussion and also the city council has been involved in that too so it's really exciting," Mr Varadkar said

In November 2012, the Government decided that St James's Hospital should be the location for the new hospital.

It followed the refusal in early 2012 by An Bord Pleanála of the application for it to be at the Mater Hospital in Dublin.

If planning for St James's is granted, building work on the €650 million facility could start next year, with it being fully opened by around 2020.

The National Paediatric Hospital Development Board said there has been extensive consultation with staff from the three hospitals moving to the new facility, families and young people, as well as residents from the local Dublin 8 area.

The board has described the planning application as a "world class design".

Speaking on RTÉ's Morning Ireland, Project Director John Pollock said today is a milestone for the project and there has been a huge amount of consultation with patients, staff and residents.

Mr Pollock said the project was made up of several elements, including satellite centres at Connolly Hospital in Blanchardstown and Tallaght Hospital.

He said this will allow children with a "routine injury" to go to their local centre rather than having to travel to the city centre.

Mr Pollock also said he presumed An Bord Pleanála would make its decision around February 2016.

He added that he believed the satellite centres will need to open in 2017.

Special Adviser to the Children's Hospital Group, Professor Owen Smith, said that St James's Hospital campus is the most appropriate location for the hospital because it has very strong, internationally recognised clinical research and educational culture.

Speaking to RTÉ's Drivetime Professor Smith said the hospital will also have a state-of-the-art research and innovation centre on the campus.

Meanwhile, the New Children's Hospital Alliance has questioned whether there is any evidence to suggest that co-locating the new hospital with an adult hospital will improve clinical outcomes.

Alliance spokesperson Dr Finn Breathnach has said there was no evidence that co-location had that effect.

Speaking on RTÉ's News at One, he said: "In an era of evidence-based medicine, it is not unreasonable to ask the question well: 'Where is the evidence for this?'

"And of course a committee, the location task group reviewed the literature on this and couldn't find a single paper supporting adult co-location.

"Paediatricians look after children, adult physicians and surgeons have no training whatsoever in caring for children. They're not needed."

Dr Breathnach said the new hospital should be located on Government-owned land near Connolly Hospital Blanchardstown principally because it is more accessible.