CCTV stills have been released of men sought by police after a cash box was stolen from a security guard in Soham.
A guard working for G4S was outside Lloyds Bank, in Churchgate Street, at about 12.45pm on New Year's Eve when he was approached by two men after leaving his van.
The offenders ran off towards Fountain Lane and were seen leaving the area on a yellow and orange motorbike.
The men were wearing dark clothing.
Det Con Paul Atkinson said: 'There were a number of people in the area at the time of the incident and I would urge anyone who witnessed the robbery to get in touch.
'I'm also keen to hear from anyone who recognises the two men or has any information about the motorbike used.'
A spokesman for Lloyds bank could not confirm how much money was stolen but said staff were helping police with their inquiries.
A spokesman for G4S said: 'This incident is currently under investigation so it would be inappropriate to comment further at this stage.
'We take the safety and security of our staff extremely seriously, and we work closely with the police and our technology providers to give our staff the best possible protection. Our staff have the right to expect to be able to go about their duties without fear of attack and we are working with the police so that those responsible for this incident can be made accountable for their actions in court.'
Anyone with information should contact Det Con Atkinson on 101 or Crimestopppers, anonymously, on 0800 555 111.
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