The main terminal will be expanded with a focus on improving the arrivals and departures hall for international passengers by installing longer baggage belts, a larger duty-free precinct and a bigger security screening area.

"Our aim is to provide a seamless, connected experience from the time you drive into the airport until you board your aircraft and vice versa," Adelaide Airport Managing Director Mark Young said.

Queensland construction company Watpac will complete the work which is expected to create 200 construction jobs and be finished by 2021.

Mr Young said while the airport currently had the ability to deal with extra planes in term of gate capacity it was reaching capacity within the terminal.

"Since we opened the existing terminal in 2005, our overall passenger numbers have increased by close to 50 per cent. Our international passenger numbers alone have almost tripled over the same period," Mr Young said.

Tourism Minister David Ridgway said the expansion would help attract more tourists to the state.

"This redevelopment will enhance South Australia's ability to attract more international airlines and accommodate an increase in the frequency of air services in the future," Mr Ridgway said.

The construction work is expected to begin within the next two weeks.

Australian Associated Press