A gadget that promises to turn almost any regular watch into a smartwatch is being developed in the US.

The Chronos pad can light up and vibrate when your smartphone receives new messages or calls.

It is expected to cost $99 (£66) when it goes on sale in 2016, making it less expensive than an integrated smartwatch.

However the device does not have a screen or voice control as found on most fully-featured devices.

The company's co-founder Mark Nichol told BBC technology reporter Chris Foxx he had focused on including the most 'critical' functionality.