The online retailer Amazon has reported a 21% increase in sales for the fourth quarter of last year.

This saw its sales hit US$87.4bn (€79.2bn), while operating cash flow increased 25% to US$38.5bn (€34.9bn).

The company says that operating income increased to US$3.9bn (€3.5bn) and its net income grew to US$3.3bn (€2.9bn) in the fourth quarter - compared with US$3bn (€2.7bn) for the same period in 2018.

Jeff Bezos, Amazon founder and CEO, says a chunk of this is down to an increase in membership of its Prime service.

This sees delivery charges scrapped on packages and also offers a TV streaming service.

The company says it now has over 150 million paid Prime members around the world.

On this, Mr Bezos says: "We've made Prime delivery faster - the number of items delivered to US customers with Prime's free one-day and same-day delivery more than quadrupled this quarter compared to last year."

"Prime members watched double the hours of original movies and TV shows on Prime Video this quarter compared to last year, and Amazon Originals received a record 88 nominations and 26 wins at major awards shows."

File photo of an Amazon Echo smart speaker | Image: Andrew Matthews/PA Wire/PA Images

Prime Video received eight Golden Globe Award nominations, with 'Fleabag' winning Best Television Series, Musical or Comedy - as well as Best Performance by an Actress in a Television Series, Musical or Comedy for Phoebe Waller-Bridge.

In Ireland, Prime offers two-day priority delivery to customers.

The firm also says customers ordered "tens of millions" of its smart devices over the Christmas period.

Its best-selling devices were the Echo Dot, Fire TV Stick 4K with Alexa Voice Remote and the Echo Show 5.

It says its Fire TV service now has more than 40 million active users worldwide.

While in September, the company pledged it will meet the Paris Climate Agreement 10 years ahead of schedule.

It has said it will reach 80% renewable energy by 2024, and 100% renewable energy by 2030.

The company is investing in wind and solar renewable energy - including a number of wind farms in Ireland.

It is developing two farms in Cork and Donegal that will be used to power its web services data centres.