Rules for liquids in hand luggage are being tightened again at airports throughout the European Union beginning on September 1.

Passengers would once again be limited to containers of no more than 100 millilitres.

Passengers are also required to pack liquid containers together in a single transparent plastic bag with a maximum volume of 1 litre.

The liquid rules, which were introduced back in 2006, had been loosened at some German airport checkpoints if baggage could be checked using computer tomography scanners.

This used a technology developed for medical scans that can quickly draw a three-dimensional image of a bag’s contents.

But EU officials have raised doubts about the reliability of the new CT baggage scanners.

The German Federal Police and Frankfurt Airport operator Fraport has drawn attention to the looming rule change on Wednesday.

The looser rules, which had permitted liquids to remain inside bags, are now a thing of the past at least for the time being, pending a security review of the new scanners.

Medication and liquid baby food are exempted from the liquid rules.

New EU regulations allowed the liquid containers to remain inside of baggage at checkpoints equipped with new scanners, instead of being removed.

However, liquids and electronics must still be unpacked and presented separately at checkpoints with conventional scanners, which were still common at many airports in the EU, including in Germany. (dpa/NAN)