Moves in the US Congress to put financial pressure on Sudan to stop the killings in Darfur have been stymied by big business interests and the Bush administration, according to supporters of legislation blocked in the Senate that would have endorsed decisions by US states to divest from companies involved in Sudan.

Tens of billions of dollars in equity are at stake, mostly of non-US companies and including two listed Chinese energy giants involved in Sudan's rapidly growing oil industry which fuels the military with arms and other supplies.