Small business owners have slammed Canberra's stubbornly high fuel prices, saying they are being unfairly penalised simply because they live in the national capital.

They have spoken out in submissions to the ACT Legislative Assembly inquiry into fuel prices, which heard from international price monitoring company Informed Sources in its first public hearings on Thursday.

Jason Tankard, who runs Printing by Tank - Design Print Canberra and Health With Tank, has been unable to afford the second car he and his family need because of the costs involved in running one, particularly around petrol. Credit:Elesa Kurtz

Chief Minister Andrew Barr and Consumer Affairs Minister Shane Rattenbury announced moves to establish the select committee last month, following a Sunday Canberra Times campaign.

They declared Canberrans were being "gouged at the pump" and said there had been no credible reasons put forward to explain disparities between the prices in Canberra and other parts of the country, including surrounding parts of NSW where petrol was cheaper despite there being little or no competition.