Seven new, longer trams are to begin operating on Dublin's Luas in 2017.

The new 'Citadis' trams are seen as the next important step for the Cross-City project.

The new trams will be a longer version of the type currently being used on the Green Line - increasing from 43 metres to 54.6 metres.

This will allow for 60 additional passengers to be carried - a total of 369 people per tram.

Speaking at the St Stephen's Green station, Transport Minister Paschal Donohoe said: "Placing the order for the new trams today, is another important step in this project".

"The new trams will carry more people and allow the Luas Cross-City extension to provide a frequent, efficient and integrated transport option for the city centre and all the way to Cabra".

The tram-stop platform lengths on the Luas Cross-City are already designed to accommodate the longer trams.

While the original Green Line platforms between St Stephen's Green and Sandyford will be extended in length in advance of their delivery.

The new trams, costing €36.5m excluding VAT, are to be ready for service at end of 2017.