Apple has said that it did this to "prolong the life" of the devices and maximise diminishing battery power.

The lawsuits were filed in California and Chicago by groups of iPhone users representing others, who they claim have suffered "economic damage".

Apple has been contacted for comment.

In the California court papers, Stefan Boganovich and Dakota Speas, who both live in LA, cite loss of use, loss of value and the purchase of new batteries as reasons for compensation, claiming that iPhone owners never consented to the "interference".

James Vlahakis, of the Sulaiman Law Group is representing the plaintiffs in the Chicago legal action.

"Apple's failure to inform consumers these updates would wreak havoc on the phone's performance is being deemed purposeful, and if proven, constitutes the unlawful and decisive withholding of material information," he said in a statement.

Mr Vlahakis added that in his view it would be a "direct violation" of consumer fraud-related legislation in Illinois, Indiana and North Carolina, where the complainants are based.