Nokia has admitted that some of its mobile phone chargers could have a shocking surprise in store for their owners.

During a routine quality control process, the Finnish phone giant discovered that the plastic covers of some chargers may work loose and separate from the adaptor's innards. The result could be a nasty shock if you touch the internal components with the charger still attached to the mains.

Nokia said it isn’t aware of the chargers – manufactured by China's Huizhou BYD Electronic, according to labels displayed on Nokia's website – yet causing anyone any harm.

The affected chargers are the AC-3E and AC-3U models, manufactured between 15 June and 9 August 2009, and the AC-4U, manufactured between 13 April and 25 October 2009.

To find out if your Nokia phone charger is affected, check out the firm’s website.

Free replacements will be offered to those at risk, Nokia promised. ®