Talks are under way between the ACT government and Canberra Airport to introduce a public transport service to the terminal.
Labor pledged to introduce the service by 2020 in the lead-up to last year's election.
Transport Minister Meegan Fitzharris said buses could be introduced sooner.
"Transport Canberra and the airport are currently engaged in discussions regarding the provision of public transport services," she said.
"The ACT government recognises the importance of Canberra Airport to the economic prosperity of our city.
"We worked closely with the airport to attract international flights to Canberra. We will continue to work with the airport on other matters, including public transport connectivity."
An airport spokesman confirmed the talks.
*Canberra Airport is working with the ACT government on how best to serve the terminal and to grow the services to the airport business park precincts. Those discussions are productive and positive," she said.
A 2011 submission to the Productivity Commission revealed the airport was subsidising the private shuttle and the spokesman confirmed this was continuing.
The 2015 MOU between the airport and ACT government committed to "working collaboratively ... to integrate the airport with rapid transit networks, Capital Metro and the ACTION bus network".
In 2013 the airport proposed a light rail network around Lake Burley Griffin to link Canberra city to the airport.
The airport's 2014 master plan also discussed liaising with the government to develop the bus network operating to and from the airport precincts.
"This may include additional routes as well as additional services on existing routes to further integrate the site within the wider public bus network," the document says.
Public transport advocate David Johnston called for terminal transport improvements to be fast tracked.
Mr Johnston said the existing private shuttle had limitations including a poor timetable and no wheelchair access.
"It is one of great mysteries of Canberra why there is no public transport to and from the Canberra Airport terminal," he said.
"Most cities have public transport servicing their airports and have had for several years now.
"Many locals and visitors want airport public transport and find it strange that there is not a service.
"It's odd the ACT government is spending billions of dollars on light rail, but won't provide an airport bus service."
Mr Johnston said public transport should be introduced before 2020 given the introduction of international flights and increased visitor numbers.
In welcoming the additional taxis, airport managing director Stephen Byron acknowledged concerns with long queues and delays for passengers.
"Our services to our passengers go beyond an efficient and friendly transit onto their flights," he said.
"We aim to provide an equally efficient transport service into the city and beyond."