The Department of Defence has launched an investigation to determine whether staff contact details were leaked to a union before a telephone campaign urging employees to reject a proposed pay deal.
The claims, which have been categorically denied by the Community and Public Service Union, were raised after complaints from non-union and former union members.
The investigation comes after an unprecedented marketing campaign by the department with management providing 51 bulletins and 98 staff meetings before the vote.
The two per cent a year wage increase was rejected by the department's 18,000 civilian employees on May 2 with a margin of 2 per cent, or about 279 votes.
In a letter to CPSU officials, the department's assistant secretary, John Geering, confirmed an investigation would determine whether contact detailed had been "inappropriately" supplied to the union.
"Defence does not believe that the CPSU would seek to gain access to personnel records or knowingly use inappropriately obtained information," he said.
"However, given the complaints we have received, Defence is now investigating whether someone has inappropriately accessed personnel records without authorisation and misused defence ICT resources, for the purposes of providing the CPSU with employee contact details."
Mr Geering said the department had received a number of complaints from employees who did not recall supplying their contact details to the union.
"Defence understands from some of the complainants that the CPSU may have received some complaints directly," he said.
In response, CPSU deputy national president Rupert Evans dismissed the claims and said it was not unusual for employees to forget supplying their contact details at some stage.
"As the responsible national CPSU official for CPSU members in Defence I can state categorically that no one has provided CPSU with employee contact details obtained through inappropriate access of personnel records," he said.
"When CPSU contacts an employee who is not, or has not been, a member of the CPSU, we do so using information they have provided to us."
Pre-recorded calls from the unionurged staff to reject the enterprise agreement as it would result in "a very small pay rise at the cost of many of our existing rights and benefits".
"I have been involved in many agreement negotiations and this is the worst offer I have ever seen," the call said. "We should not settle for anything less than a fair agreement and we need to vote no to secure our conditions."
In a newsletter to staff earlier this month, the department assured staff it had not supplied contact details to any union or third party.
Mr Evans said the response from Defence was "more about sour grapes than a genuine desire to try and resolve this dispute fairly."
"Our calls were all about providing Defence staff with the balanced information they needed to make an informed decision," he said.
"We made many thousands [of] calls and the feedback was overwhelmingly positive. Fewer than 20 people asked not to be contacted again.
"Many more staff complained to us about being bombarded by the department with 10 email bulletins in 10 days as Defence tried to strong-arm people into approving their poor offer."