During the last government, Mr O'Leary became embroiled in a bitter war of words with Mr Ryan over the Dublin Airport passenger cap, and posed for photos beside cardboard cutouts of the faces of Mr Ryan and then tourism minister Catherine Martin in 'dunce' hats.

Asked about the Ryanair chief, Mr O'Brien said: "I like him. I do have a lot of respect for him. I think he has a different style. He's kind of brash, he says it as he sees it. 

"Do I think he's always right? No, but I've got to respect the fact that he's a guy who has built the most successful airline in Europe and the largest airline in Europe."

Dublin Airport

The transport minister has committed to lifting the cap on Dublin Airport passenger numbers but stressed that he is "not doing it because of Michael O'Leary", and instead the restriction must be eased to ensure international connectivity and economic growth.

The Government has promised to enact a law by mid-July that would see the 32 million annual cap on passenger numbers lifted. This limit is ​currently suspended pending a European Court ruling.

Dublin Airport, which carries around 80% of the country's air traffic, overshot the limit by four million ​passengers last year.

However, environmental groups have strongly warned against lifting the cap and the Oireachtas Transport Committee last month recommended that the Government should carry out an environmental and climate impact assessment of its plans to remove the passenger limits.

Mr O'Brien told the Irish Examiner: "We can't have false inhibitors to growth. I'm pro-aviation. It's good for jobs, it's good for our economy. I think he (Mr O'Leary) has been pretty tough on my predecessor; he's been tough on the Taoiseach as well.

"He has a very different style, but aviation and that sector runs in his veins, and he's someone who can't be ignored, and I think we have a decent relationship."

Mr O'Brien added that it is important for members of Government to "reach outwards" to seek advice from leaders in the private sector.

"I do lean on people who are disruptors, and you don't have to be disruptive to be constructive, though. That's the only thing, you can be constructive without being disruptive," he said.

Grants for renewables

Separately, Mr O'Brien highlighted the significant uptake in grants to retrofit and install solar panels on homes.

He said he is now looking at introducing grants to allow households to install batteries to store excess energy generated by renewables.

"I want to be clear to people, though, the grants that are there at the level they are at will remain at the level they're at. But I am looking at what we can do for domestic battery storage."

Mr O'Brien said he also wants to streamline and simplify grants to businesses and indicated that these changes could be in place as early as July.

"That's not necessarily about more money, what it's about is actually making supports more accessible, like we've done on the domestic retrofit grants," he said.

• Elaine Loughlin is political editor of the Irish Examiner