WORKERS who fill and maintain cash machines are threatening to strike over an “insulting” refusal to increase their pay by G4S Cash Services, their union said today.

GMB, which tabled a 7.5 per cent pay claim on behalf of its 1,400 members, said that action could paralyse “cash in transit” services, leaving cash points empty and travellers unable to obtain foreign currency.

The union has given the company, now owned by Allied Universal, notice of a ballot which could see members walk out at a time when labour is in great demand across the industry.