West Australian Premier Colin Barnett has been filmed during an awkward moment insisting a Big Issue vendor hand him his change.

As he left the ABC studios in East Perth on Thursday, Mr Barnett bought a $7 magazine but waited after he handed the seller two $5 notes.

After she told him "I'll talk to you again in the near future with the next edition", he replied "OK, are you going to give me my $3 change?" then laughed.

Opposition treasury spokesman Ben Wyatt expressed shock when he saw the video.