Low-cost airline Ryanair has launched its Black Friday promotion by putting some 10 million seats on sale on its website.

The Irish carrier, which launched its eight-day "Cyber Week" campaign earlier this week, said on Friday (25 November) that it will offer up to 20% off on flights, adding passengers will be able to book their seats until midnight tonight.

Ryanair, which did not offer any details over the routes involved, added discounts will only be available on flights departing between December and March and has urged its customers to keep an eye on its Facebook and Twitter pages to remain updated with the offers.

Ryanair's Robin Kiely said the offer was the biggest Black Friday promotion in the airline's history.

"It's Black Friday and as the largest airline website in the world, there's no better place for online bargains than Ryanair.com," he added.

"We knocked up to 20% off 10 million seats, for travel from December to March, as part of our biggest ever Black Friday promotion. This incredible offer is only available until midnight tonight, so customers should log on to the Ryanair.com website to book a Black Friday special today – and watch out for more huge savings this weekend."

On Monday (21 November), the Dublin-based airline kicked off its "Cyber Week" promotion by putting 250,000 seats on sale from £9.99 – on one-way flights – on over 400 routes, for travel in January and February.

Earlier this month, Ryanair chief executive Michael O'Leary's said average fares will fall between 13% and 15% on flights to and from the UK over the next six months.