In November, city-based public relations firm the Content Group was awarded a contract for the development of a 12-month program of strategic "communications and engagement activities" to promote the $800 million project, with construction scheduled to begin next year.

Documents published on the ACT government procurement website show the two-stage process will include research and planning with Capital Metro Agency executives and other stakeholders.

The company will be required to consider audiences, content, channels, publishing, measurement and evaluation of activities planned to promote the case for the city to Gungahlin tram line.

The total value of the contract is $26,895.

"A calendar of events will be provided to the [ACT government] that outlines the media events and stories to be rolled out over 12 months," the contract documents show.

"The contractor will provide a plan to the Territory outlining engagement with third-party advocates."

The Content Group has worked regularly for the ACT government, including on other aspects of the light rail project and on last year's trade mission to China and Singapore.

Managing director David Pembroke and communications director David Polglase are listed as personnel on the contract, along with consultant Michael Cooney.

Mr Cooney is a former chief of staff to Chief Minister Andrew Barr and currently heads the Labor Party's national think tank, the Chifley Research Centre.

Opposition transport spokesman Alistair Coe said the contract was only the latest example of large spending to promote the tram line.

"Over the last year, the ACT government has spent more than $300,000 promoting light rail and this is another example of desperate wasteful spending," Mr Coe said.

"If light rail was good policy, the government wouldn't need to devote such time and money in order to sell the project."

The Canberra Liberals are yet to outline a substantive public transport policy but won't proceed with further development of light rail if they win government.

Last year, Opposition Leader Jeremy Hanson said more detail of the policy would be released in 2015.

"Simon Corbell and Shane Rattenbury can't effectively sell light rail, so they are using taxpayer's money to try and do it for them," Mr Coe said.

"It speaks volumes that if the major proponents can't sell a pet project, it mustn't be worthy of such a huge expense."

Capital Metro Minister Simon Corbell said the project's benefits to Canberra included jobs, reduced traffic congestion and shorter journey times.

In a statement, he said spending on external communications services was not unusual for major ACT government projects.

"Considering the importance of this major infrastructure project it is completely appropriate that the government uses the best possible avenues to keep the community informed and engaged along the way.

"The ACT government places high priority on communicating and engaging with the community on large projects, and wants to ensure that it does this effectively by using an established local supplier with extensive experience in local communications activities," Mr Corbell said.