Online retailer Amazon has announced it will give away digital versions when customers buy CDs and vinyl records – and they will be backdated for any past purchases from 1999 if a digital version is available.

The free MP3 service, called AutoRip, will enable music fans to have instant access to music they have bought – several days before their purchases arrive in the post. The company has already lined up more than 350,000 albums for AutoRip with more to be added, and said there will be no knock-on effect on prices.

Tracks will be added to their Amazon Cloud Player account and can be either streamed or downloaded to devices such as iPhones, iPads, Kindles and smartphones.

AutoRip will not work if items were bought as gifts for other people and it doesn‘t apply to items bought from private sellers in the Amazon Marketplace – only those bought directly from Amazon.

Latest figures for the UK market show Amazon became the leading music retailer in 2012, accounting for 25.6% of expenditure (15.3% for home delivery and 10.3% downloads) and taking over from troubled HMV which had been ahead the previous year.

But iTunes is leading the way for digital sales, and represents 22.5% of the entire music market – up from 17.9% the previous year – according to data from Kantar Worldpanel, which is used by the British Phonographic Industry.

Both companies are looking to push up their share, particularly after HMV‘s administration earlier this year.

Jeff Bezos, the CEO and founder of Amazon.com, said: “What would you say if you bought CDs, vinyl or even cassettes from a company 14 years ago and then 14 years later that company licensed the rights from the record companies to give you the MP3 versions of those albums and then, to top it off, did that for you automatically?

“Well starting today, it‘s available to all of our Amazon.co.uk customers – past, present and future at no cost. We love these opportunities to do something extra for our customers.”