The Ministry of Foreign Affairs of the Netherlands has sent out a letter warning Dutch travellers visiting Turkey, China, Russia and Iran that their electronic devices may be unsafe in these countries, BBC Türkçe reported on Monday.

The ministry warned that data on electronic devices, including laptop computers and smartphones, may be read and copied by third parties in these countries, and said that sensitive information should not be carried on these devices under any circumstances.

The ministry sent the warning as Dutch Prime Minister Mark Rutte prepares for a trade visit to China alongside bureaucrats and representatives of 165 companies.

“It is painful, but the warnings on cyber espionage will also apply to our NATO ally Turkey, as well as Russia and Iran,” BBC Türkçe quoted a foreign ministry source as saying.

The warning letter includes a list of recommendations for Dutch nationals travelling to the four countries – firstly stating that travellers should take a “clean” laptop and mobile device with updated security software. “Only absolutely necessary data should be carried on these devices,” it continues.

Further safety precautions include a warning to leave the wireless data transfer tool Bluetooth switched off throughout the entire trip, and to password protect data storage devices.

The message also advises travellers to turn off their Dutch telephone and use a new device and sim card while visiting the four countries.

Turkey’s relations with Holland suffered a setback in April 2017, when Dutch authorities refused to allow members of Turkey’s ruling Justice and Development Party (AKP) to hold rallies for Turkish citizens in Holland.

The ensuing war of words led to Holland withdrawing its ambassador to Turkey and refusing to allow the Turkish ambassador to take up duties in the Netherlands. Relations have still not normalised despite talks in February.