Police investigating a series of letter bombs earlier this month have arrested a man in Cambridge.

The authorities have also warned there might still be devices in the post en route to UK addresses.

Earlier this month, letter bombs exploded at Capita, the firm which administers London's congestion charge, an accountancy firm with links to a speed camera firm, and the DVLA. This led to suspicion that the culprit was an angry motorist. A total of seven devices were sent.

Association of Chief Police Officers' national co-ordinator for domestic extremism Anton Setchell said in a statement:

We have now reached a very significant stage in this enquiry. During the early hours of this morning, police arrested a man in the Cambridge area; he is now being held at an undisclosed police station.

As a result of his arrest, I am somewhat restricted in what I am able to say.

Forensic search teams are commencing what is going to be a lengthy search of a residential address in Cambridge. I anticipate that this will last for several days.

Setchell warned it was possible a letter bomb was still in the postal service, and warned the public to be extra wary of any dodgy looking mail. The devices were sent in A5-sized Jiffy bags.

He said the public should "maintain their vigilance" and also asked for people to restrain from speculating about what action the police were taking.

See the whole Acpo release here. ®

• Union accuses Capita on job losses (21 January 2008)
• Cambridgeshire letter bomber found guilty (27 September 2007)
• UK supermarkets fingered in crap petrol probe (28 February 2007)
• Man due in court on letter bomb charges (23 February 2007)
• ViSOR numbers creep towards 100,000 (22 February 2007)
• Analysis Letter bombs: an expert writes (7 February 2007)
• Updated Third letter bomb at DVLA (7 February 2007)
• Accounting firm hit by letter bomb (6 February 2007)
• Capita hit by letter bomb (5 February 2007)