US politicians reportedly followed in the steps of South Korea and Japan by pressing ahead with proposals to tighten rules on app store providers Google and Apple.

Bloomberg reported Senator Amy Klobuchar, chair of a competition subcommittee, is spearheading the campaign, which it noted weighed more heavily on Apple than Google.

Klobuchar told the news agency the plan includes requiring alternative app stores and payment methods to be offered, and enabling developers to access elements of iPhone hardware currently available only to Apple.

She was reportedly dismissive of a recent move by Apple to offer more app-related payment options to users, stating it did not go “nearly far enough”.

Apple issued its pledge following a probe by Japanese authorities, while South Korea recently became the first nation in the world to mandate alternative app payment platforms be made available.

Google and Apple are in the firing line globally as concerns grow over their hold on the app marketplace.