Vodafone has issued an apology after exposing the private email addresses of hundreds of its mobile broadband customers.

The telecoms company was prompted to get in touch with 416 of its customers as it moved to correct a recent billing error which saw them charged £5 for signing up to its 'free' Mobile Internet Access promotion.

However, rather than sending out blind carbon copies (BCC) of its explanation to a mailing list of affected customers, Vodafone inadvertently sent out the communication through the CC method, thereby exposing all of the private email addresses in the list.

Contacting website The Register to explain the malfunction, Vodafone insisted that this was the first time it has mistakenly made its customers' information available, with "human error" blamed for the episode.

This embarrassing development comes just days after Vodafone announced the upcoming launch of its Access Gateway signal-boosting technology, designed to increase the strength of mobile phone signals by routing calls through a home broadband internet connection.