Anti-dumping authorities are investigating whether canned tomatoes exported from Italy and sold as Coles and Woolworths home brand products are being dumped at cheap prices to damage local growers.

Both supermarket chains are selling 400-gram tins of diced Italian tomatoes for $1.10 under their own labels. Ardmona, the brand made by major local fruit processor SPC, is sold at $2.10 for a 400-gram tin of diced tomatoes that are grown and packaged in Australia.