Buildings in Dublin will have to be "much higher" to accommodate the number of people living in the city centre as the capital's population approaches two million, Minister for Social Protection Leo Varadkar has said.

Setting out his vision for the city, Mr Varadkar also said Dublin faces two "existential challenges arising from the disastrous cycle of boom and bust" - housing and transport.

He added that he is a "passionate advocate" of a single mayor for Dublin, with his preferred option being an elected executive like in London or Paris. The Dublin West TD was speaking to the Dublin Chamber of Commerce, and urged the group to take a strong position on the mayor proposal, which is being debated in the Dail.

With the city's population set to reach two million by 2030, Mr Varadkar said Dublin will "truly be a world city with a large economy", which he described as a "huge opportunity".

He spoke of how he does not want Dublin to be like an American city that empties at night.

"We should aim to increase considerably the population living between the canals and in the near suburbs. To do so, we need to build much higher outside the Georgian core," he said.

Emulate

The city should be "adventurous" in its architecture and should try to emulate London or Barcelona, which have "world-famous" new buildings.

Mr Varadkar warned against the kind of 1950s and 1960s "eyesores that still blight some parts of the city", giving the example of his old office as health minister, Hawkins House, which is slated for demolition.

He suggested rooftops could be turned into gardens, cafes or performance spaces.

On transport, he said the most pressing issue was how to help commuters as the M50 reaches peak capacity.

He said more Luas lines to places such as Lucan and Ringsend and more bus services are needed, but warned that "public transport infrastructure does not come cheap".

"What is required is the political will now to prioritise some of these projects," he said.