Ryanair has signalled a return to growth in Scotland, announcing six new routes from Edinburgh and two from Prestwick next summer.

The no-frills airline will also increase the frequency of its existing services and all but reverse two years of decline in which passenger numbers have fallen by 18%.

At Edinburgh, it will launch new services to Bologna, Beziers, Cagliari, Corfu, Katowice and Santander, taking the total number of destinations to 38, while increasing flights from 232 to 246 a week.

Prestwick will see new routes to Rzeszow & Warsaw Modlin, taking the total to 27 routes and increasing the number of weekly flights from 86 to 95.

Overall passenger numbers in Scotland are expected to reach 3.2 million in 2013, an increase of 15% and just shy of the peak of 3.3m seen in 2010.

Ryanair said the enhanced route network would deliver 400 new jobs between Prestwick and Edinburgh, though the industry formula it uses to calculate the figure has been widely described as overly optimistic in the past.

The announcement follows a turbulent few years for Ryanair, which cut its winter schedule at Edinburgh earlier this year following a disagreement over landing charges with its previous owner, BAA, and has presided over a steep drop in passenger numbers at Prestwick.

Speaking at a press conference in Glasgow, the airline’s chief executive Michael O’Leary admitted that a deal struck with Global Infrastructure Partners, which took over the running of Edinburgh Airport in summer, did not include the reduction in landing fees which he had tried and failed to secure with BAA, its previous owner.

But he said the company, which also owns Gatwick Airport, was “committed to growth” in contrast to BAA, which still owns Glasgow and Aberdeen airports in Scotland.

He blamed the downturn at Prestwick, which was put up for sale in March by its New Zealand-based owner Infratil after it was described as “under performing”, on increases in Air Passenger Duty, which is paid on all departing UK flights.

This had had a particularly damaging impact on short-haul flights and spelled the demise of the Prestwick to Stansted service, he said. “We haven’t been growing significantly in Scotland in recent years and that’s because APD has hit domestic aviation very strongly,” Mr O’Leary said.

“Passengers are suffering both sides of the route - on the departure and return flight - and as a low-fare airline, the effect is even worse. We have been campaigning with the Scottish Executive to have this changed. I’m a great believer in Scottish independence - as long as we get rid of APD, I’m all in favour of it.”

Gordon Dewar, chief executive of Edinburgh Airport, said it was clear he had to “repair” the relationship with Ryanair when he was appointed. “It’s great to find a new, long-term relationship with what is the most important airline in terms of growth going forward,” he added.

The announcement was also welcomed by Tom Wilson, chief executive of Infratil Airports Europe, who said it would help reassure potential investors that Ryanair had a long-term commitment to Prestwick.