Berlin - As ever more people worldwide pick up smartphones, tablets and other gadgets, the amount of data being stored is raising questions about what's being gathered ... and by whom.

A lot of the data is automatically generated by networked machines - smartphones, energy metres, surveillance cameras and cars with satellite navigation systems. Their share of gathered data will rise to 40 percent by 2020, predicts storage specialist EMC. In 2005, that share was 11 percent.

“The internet of things is constantly creating more data,” says Sabine Bendiek, German head of EMC.

It doesn't help that users are saving ever more. EMA estimates that stored data for 2012 will reach 2.8 zettabytes, or a 2.8 followed by 21 zeroes. By 2040 it could be 40 zettabytes.

The spread of the internet to developing economies also helps account for the increase. The amount of information generated in these countries is supposed to reach 62 percent of the total by 2020, dwarfing that produced by Europe and America.

Germany's federal commissioner for data security, Peter Schaar, has raised concerns about the flood of data.

“We have invisible data gatherers in our smartphones, cars and other devices, that are always generating data,” he said. “That worries me greatly.”

He said apps need to be designed so that data cannot be shared without permission. - Sapa-dpa