Amid a slew of complaints about reduced battery life in older iPhone models, Apple in a rare statement admitted that the company has introduced software updates in older models in order to optimise battery performance, CNN reported on Friday.

Apple issued an official statement earlier this week after users accused the company of introducing software updates that cause phones to slow down as a ploy to get people to buy the new model.

According to the tech giant, lithium-ion batteries slow down with time and can cause the phones to shut down suddenly in order to prevent damage to components.

In order to avoid such occurrences, the new software updates in iPhone 6, iPhone 6S, iPhone SE and iPhone 7, were introduced to "smooth out" peak power demands and extend battery life, the statement said.

The company further stated that it will introduce similar updates in its other products as well because the brand wants "to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices".

However, the updates often lead to agonisingly slow speeds and response times as the devices reorder commands instead of parallel execution.