TRAIN drivers and station staff on the Mass Transit Railway yesterday decided to launch a potentially year-long protest campaign against what they call an unfair pay adjustment. Members of the 500-strong MTR Operating Staff Union said management's offer of a seven per cent pay increase plus merit money was unacceptable, and staff now needed an extra 3.23 per cent wage rise to make up for back pay since 1991. The union said it had asked for 10 per cent plus merit money to make up for the shortfall, but MTR managers had refused. From August 1, union members will wear protest badges at work, and if MTR management does not attempt a compromise by next summer the union will decide whether to start a work to rule. But MTR management said the real pay increase was 11 per cent because every member of staff would be getting an extra four per cent merit money. ''Every employee will get the merit money, without exception, unless they have only been with us for a short time,'' said an MTR spokesman. ''The corporation is giving them 11 per cent at the end of this month. We used to give the merit money in January and the pay rise in July, but now we are doing it all at the same time.'' The union said it was misleading to include the merit money. ''Merit money is not a pay rise. It is something that is within the gift of the management. They can take it away if they want to,'' said the union's vice-chairman Leung Chi-shing. The badge campaign would raise public awareness and increase support for the pay claim among the MTR's workforce, Mr Leung said. The union would wait for the outcome of the next pay review before deciding what action to take, he said. One option was for drivers to mount a ''safety campaign'', keeping train doors open beyond the normal two minutes to stop passengers rushing onto the trains. Mr Leung denied the union was waiting until next year before it took action because it did not have the strength to do so now. ''We just have to be realistic,'' he said.