The regulators have recently circulated a new round of questionnaires focusing on Apple's new "core technology fee", the report said.

For those who came in late, Apple released a wave of different fees which it claimed would solve the issue of developers having to pay up to a third for the privilege of being in its walled garden of delights.

In fact, Apple levied a new charge of 0.50 euros per installed app on developers claiming that would enable it to comply with the bloc's Digital Markets Act (DMA).

The DMA imposes what the world's largest tech platforms can and cannot do and can impose fines up to 10 per cent of a company's annual revenue if it tries to get out of it.

Now it seems that some developers have pointed out to regulators that instead of reducing how much they had paid, they were now paying more.

Regulators are checking whether the re-jigged levies could be passed on to consumers, or if developers may have to tweak their own business models due to Apple's new fee structure, the report said.

The regulators have recently circulated a new round of questionnaires focusing on Apple's new "core technology fee", the report said.

EU's fresh scrutiny also comes at a time when Big Tech bosses have urged President-elect Donald Trump to challenge EU's regulatory scrutiny against them.

They also asked whether the firm's prediction that the new system will help reduce costs for developers is accurate or not.