Jetstar flight diverts after 'unusual smell' makes crew sick

A Jetstar flight has been forced to return to Melbourne after at least crew members became unwell during the flight.

The Airbus A320 departed Melbourne at 11.45am bound for Adelaide but turned back shortly after taking off.

The plane landed safety just after 12.15pm but two crew members have been assessed by medical staff.

A Jetsar spokesperson said the pair became unwell "after an unusual smell in the back galley".

"Our crew have been assessed by medical staff and our engineers are inspecting the aircraft.

"The flight has been delayed until this afternoon, with customers being reaccommodated on a replacement aircraft."

Images from the 9NEWS helicopter showed fire crews and paramedics around the plane.

There were 174 people, including passengers and crew, on board the flight.