She said: "We can no longer pretend the creation of wealth for a few will inevitably benefit the many - too often the reverse is true. Concentration of resources in the hands of the top 1% depresses economic activity and makes life harder for everyone else - particularly those at the bottom of the economic ladder."
Political and economic leaders from around the world will gather for four days at Davos from January 23. Oxfam's briefing pointed out that the World Economic Forum's own Global Risk Report rated inequality as one of the top global risks of 2013, something the IMF agrees with.
Oxfam said world leaders should learn from countries like Brazil, which has "grown rapidly while reducing inequality", and also cited former US president Franklin D Roosevelt's New Deal in the 1930s during the Great Depression.
Ms Stocking added: "We need a global new deal to reverse decades of increasing inequality. As a first step world leaders should formally commit themselves to reducing inequality to the levels seen in 1990.
"From tax havens to weak employment laws, the richest benefit from a global economic system which is rigged in their favour. It is time our leaders reformed the system so that it works in the interests of the whole of humanity rather than a global elite."