Amazon is to increase the price of its Prime membership in the US by $20 to $99 a year.
This will be the first time the online retailer has increased the cost of the service, which includes free two-day shipping on around 20m products, since it was introduced in America in 2005.
The price hike will come into force when users renew their membership. Those renewing before 17th April will pay $79 for the year, with those renewing afterwards paying the new price of $99.
New customers who start a free trial between now and 20th March will pay $79 for the first year.
The Associated Press reported that in an email to Prime members today (13th March), Amazon stressed that it had not raised the price on Prime despite the increase in shipping costs and the addition of new services including video streaming.
In the UK the cost of Amazon Prime was increased in February from £49 to £79 a year due to Amazon rebranding its LoveFilm streaming service as Prime Instant Video and including it within the Prime package, in addition to unlimited free one-day delivery on thousands of items and the right to borrow thousands of titles for the Kindle for free.
Amazon in the UK has made other changes to its services this year, which can be seen as an attempt to encourage customers to sign up to Prime.
At the beginning of the year the retailer changed its delivery terms and conditions to charge customers £10 delivery on books, CDs and DVDs for standard deliveries on orders under £10. Before 7th January, standard delivery on books was free.
The company also announced in January that it would offer Sunday deliveries in seven UK cities to Prime customers.