Members of the Shropshire group of the World Development Movement set up a 'Bankers Anonymous' stall on the High Street on Saturday outside the Shrewsbury Unitarian Church.
Organisers claim that banks and hedge funds are helping to drive up food prices through their financial speculation tactics, resulting in the cost of basic foods increasing beyond the reach of millions of the world's poorest people.
The campaign comes after Barclays announced last month that it would end its food price speculation work, with chief executive chief Antony Jenkins saying the work was 'not compatible with our purpose'.
The World Development Movement estimates the bank made £278 million from the trade in 2012.
The organisation is calling for tough controls on speculation and for other banks to follow the example of Barclays.
Campaigners in Shropshire campaigners asked passers-by to take part in a 'five step programme' for bankers to stop them speculating on food prices, with steps including signing a postcard to local MPs, asking them to urge George Osborne to act to control the practice.
European finance ministers, including George Osborne, are due to vote on draft regulation to curb food speculation in the coming months.
But the UK government has so far failed to back tough controls.
Anthony Twist, from the Shropshire group of the World Development Movement, said: "Banks need our help to quit gambling on food. Only strong regulation will stop speculation playing havoc with prices. Food is a basic human need and banks must not be allowed to gamble on it to make a fast buck."
Last month, World Development Movement campaigner Christine Haigh welcomed Barclays' decision but added more action needs to be taken.
"One of the world's biggest banks has acknowledged that gambling on food is not an acceptable way to make money," she said.
"The only thing that will prevent banks driving up prices is tough regulation, and this is what the UK government should be supporting."