After the US decided to probe Apple in possible violations of securities laws over slowing down of older iPhones, the Cupertino-based giant said it has never done anything "intentionally" to shorten the life of its products.

The US Department of Justice and the Securities and Exchange Commission are investigating Apple for how it disclosed information in software updates that slowed down older iPhones.

"As we told our customers in December, we have never - and would never - do anything to intentionally shorten the life of any Apple product, or degrade the user experience to drive customer upgrades," CNN reported, quoting an Apple statement late on Wednesday. 

Apple faced backlash after it admitted last month that it used software updates to limit the performance of older iPhone models, including the iPhone 6, iPhone 6S, iPhone SE and iPhone 7.

The goal, according to the company, was to "smooth out" peak power demands and prevent older iPhones from sudden shutdowns as their lithium-ion batteries degrade. But it resulted in disappointing performance for users, according to CNN.

Senator John Thune, a Republican representative from South Dakota, criticised the company's lack of communication in a letter to Apple CEO Tim Cook, media reported.

Meanwhile, the company said that its battery replacement programme at a discounted cost will be available from late January through December 2018.

Apple also said that in early 2018, it will issue an iOS software update with new features that give users more visibility into the health of their iPhone's battery, so they can see for themselves if its condition is affecting performance.