Budget airline Ryanair has announced eight new routes from its two Scottish bases and called for air passenger duty to be scrapped.
From next summer the airline will carry three million passengers and sustain 3,000 jobs with the additional flights, chief executive Michael O'Leary claimed.
The new routes will be from Edinburgh to both Bologna and Cagliari in Italy, Beziers in France, Santander in Spain, the Greek island of Corfu and Katowice in Poland, and from Prestwick to both Rzeszow and Warsaw in Poland.
Mr O'Leary said they will start in around six months, while nine other flights from the airports will increase in frequency.
The new routes from Edinburgh Airport are significant because Ryanair reduced its flights from there in February after failing to agree lower costs and charges with operator BAA. The airport is now run by Global Infrastructure Partners (GIP) and Mr O'Leary said further announcements on growth are likely.
"We have eight new routes out of Glasgow and Edinburgh for summer 2013, growing both airports by around 400,000 passengers that should lead to 400 new jobs spread evenly between the airports.
"We've been very impressed by GIP. They are very committed to growth and we've been negotiating now for a couple of months. I don't think today's announcement will be the last because, given their commitment, they want to grow the airport quickly and that's a breath of fresh air after dealing with BAA who only wanted to fatten profits for its eventual sale."
Mr O'Leary backed calls from all of Scotland's main airports for the UK government to scrap air passenger duty. Last month Aberdeen, Glasgow and Edinburgh airports commissioned a report that claimed the charge could lead to a drop in both passengers and tourism spending. The tax could cost the Scottish economy £210 million a year in lost tourism spending by 2016 and could lead to 2.1 million fewer passengers in Scotland's airports by then, the report claimed.
Gordon Dewar, chief executive of Edinburgh Airport, said: "The whole purpose of Edinburgh Airport is to connect Scotland to the rest of the world and we do that by working with the airlines that offer the biggest choice of routes and carriers.
"So when an airline the size of Ryanair isn't getting on with the airport, that isn't good for anyone and changing that was one of the focuses since GIP bought the airport. And today marks the successful re-establishment of a good relationship and the fruits of that labour are the new destinations and increased passenger numbers."