Kingston's fire stations could be left short-staffed for periods tonight and tomorrow night after fire fighters started the first day of work-to-rule industrial action.

London Fire Brigade said it would cover any shortages in a short-staffed area with engines from neighbouring stations.

The Surrey Comet has been told shifts starting at 6pm will be short staffed, and fire fighters finishing then will only stay until 7pm, as required by their contract, instead of staying longer to maintain full coverage as they said they often did.

One staff member, who did not want to be named, said: "I'm very concerned – I live in the borough myself and so I'm vulnerable myself."

He said there would still be staff at the fire stations, but not enough to send fire engines on calls unless staff came from other areas.

The dispute centres on bosses' plans to scrap current contracts and change shift patterns, and a ballot about formal strike action got under way yesterday, with the results expected to be announced in mid-October.

A London Fire Bridage spokesman said: "This action – effectively work to rule – means there could be some disruption to individual fire stations for short periods.

"During this action we would like to reassure Londoners we plan our fire cover to meet the needs of London as a whole. If for any reason staff or fire engines in a particular station are unavailable we allocate resources from elsewhere to provide cover.

"We provide this sort of cover every day while crews are dealing with an emergency, carrying out community safety work or training away from their station."