I have now received a clear confirmation of the policy during the exam regarding electronic devices from the EQE secretariat:
Electronic devices are strictly forbidden in the examination hall, no matter if they are turned off or not.
Any candidate found with such a device in the hall is clearly breaching the regulations, and he/she might face disqualification from the exam.
The only electronic devices which may be allowed in the examination hall are medical devices that candidates need for health reasons.
We recommend that candidates leave their mobile phone at their hotels if they are travelling.
There are no cloakrooms at the examination centre, however we will provide envelopes (you will have to write your name on it) where the device can be placed and it will be put in a box.
The box will be outside of the examination hall. Neither the Examination centres nor the Examination Secretariat will take any responsibility for loss or damage to the items stored in this box.
This is probably not the solution that you wanted, but this is becoming common practice for exams. A simple watch with an analogue dial is the only thing you can have with you.
So either leave them all at home, or in the hotel, or car, or in train station locker.