A rail link to Melbourne Airport should not come at the expense of SkyBus, because there is no guarantee enough passengers would use the train line, according to the head of the express shuttle company.

A few weeks after Infrastructure Victoria recommended a rail line should eventually be built to meet the city's long-term needs, SkyBus has weighed into the debate, saying it already provides a "world class service" in airport transport.

"Just because you build an airport rail, it doesn't mean people want to use it," said Skybus director, Michael Sewards. Credit:Roy Chu

"The reality is, just because you build an airport rail, it doesn't mean people want to use it," said the company's director, Michael Sewards.

"Yes, let's plan for the next 15 or 30 years, but let's also be somewhat sensible in this conversation by recognising we've had a service for over 38 years, which over 50 million passengers have used. We think we can co-exist with rail and provide a very competitive offering."