The budget airline will reduce services from the South Ayrshire airport to 34 a week compared to some 44 last summer.

The reduction is because the carrier is removing one of its three aircraft based at Prestwick during the summer.

The move follows Ryanair’s flights from the airport this winter being reduced from 16 to 11 a week – which is near the lowest level since it began operations there in 1994.

The airline blamed delays to new Boeing 737 Max aircraft after two fatal crashes.

However, both Glasgow and Edinburgh airports said they would see no reduction in Ryanair flights this summer.

Edinburgh said the airline would add a new route to Bydgoszcz in Poland in April.

Prestwick has built up debts of nearly £40 million since being bought by the Scottish Government for a token £1 in 2013 to avert closure.

Transport secretary Michael Matheson told MSPs last month a “preferred bidder” for the airport had been chosen, six months after it was officially put up for sale.

It is believed to be AGS Airports, which owns Glasgow, Aberdeen and Southampton.

Scottish Conservatives transport spokesman Jamie Greene said: “Further reductions is more bad news for the airport which, under Scottish Government ownership, has simply failed to attract new airlines and routes.

“Frank questions need to be asked about why the airport is proving to be so unattractive to the consumer airline market and what are the barriers hindering its growth and commercial viability.”

Colin Smyth, his Scottish Labour opposite number, said: “This is a massive blow to Prestwick. Air passenger services already make a loss at the airport but it would have taken only a small number of additional flights to change that.

“Instead, this decision is likely to increase the losses from passenger flights and raises once again their viability.

A Ryanair spokesperson said: “As announced in December, due to the late delivery of the Boeing Max aircraft, a number of Ryanair bases will be cut or closed in summer 2020. In Scotland, our Prestwick base will be reduced by one aircraft from April.

“We are working closely with pilot and cabin crew unions to minimise the impact on staff across Europe.”

A spokesperson for Prestwick Airport said: “Reductions to Ryanair’s flying schedules are widely anticipated across its UK bases owing to the much-publicised delayed deliveries of Boeing’s aircraft.

“We are meeting with Ryanair later this month to discuss additional capacity for the winter 2020/2021 and summer 2021 timetables.

“We continue to enjoy a strong relationship with Ryanair, including acting as a hub for engineering and maintenance crew.”

Ryanair slashes summer flights from Prestwick as airport awaits buyer