Early testing
The earlier autism is diagnosed, the sooner children can get access to behavioural or educational interventions.
The team at the Weizmann Institute of Science said that one of the advantages of a sniffing test was that it did not rely on the child being able to communicate so it may be useful at a very early age.
Miss Rozenkrantz added: "But before we can use it as a diagnostic test, we need to know at what age children start to develop a sniff response in the general population.
"Are you born with it? Do you develop it later in life? No-one has looked at it yet.
"I think what we have an interesting place to start, but we do have a way to go."
The researchers said smells had a role in social interaction and that this may explain the link with autism.
Dr Judith Brown, from the UK's National Autistic Society, said: "Getting a diagnosis is a crucial step to unlocking vital support services which can make a huge difference to people on the autism spectrum and their families.
"We believe that the possibility of developing a single and universal diagnostic test for autism is unlikely.
"However, in future, if these initial findings are confirmed and fully understood, differences relating to processing smell may offer an additional tool in the necessarily multi-faceted process of diagnosing autism."