WASHINGTON: Restarting a smartphone takes just a few moments, and yet it's something that many of us rarely take the time to do.

However one major US spy agency is now calling on smartphone owners to consciously turn off and on their phones at least once a week, as this helps to protect the device from certain hacking attempts.

Malware launched via spearphishing and zero-click exploits can be prevented by manually turning the device off and on again, according to a list of "Mobile Device Best Practices" issued by the cyberespionage analysts at the US National Security Agency (NSA).

Android smartphones can typically be restarted by long pressing the power button or holding the power button and the volume up button at the same time.

If you have an iPhone, you'll need to switch it off once, wait briefly and then switch it on again. You can do by pressing the lock button and the volume up button at the same time.

That's not all you can do to keep your phone safe. Here are some other tips for improved smartphone and tablet security, courtesy of the NSA:

You know all that? Then here are some more advanced suggestions tailored to people with confidential information on their phones:

 - dpa