Mr Murphy accused ministers of caring more about getting cash "out the door" than its impact.
He said: "Under Labour the Department for International development (DFID) helped change the world, but that ability is being lost because of a culture of measuring success by input instead of outcomes.
"DFID should have higher ambitions than just to act as the charitable arm of the British Government (and) development should be about much more than simply getting money out the door. It is about using the size and scale of the UK development budget to bring about social justice across world borders. I want to see change not charity."
His criticism comes amid growing calls for overseas aid money to be diverted to help people struggling with floods across England. There is also increasing public debate about the kinds of countries and programmes that the UK development budget should fund.
The Coalition Government has already bowed to critics and vowed to halt aid to India, a country that is building its own space programme, by 2015.
Central to Mr Murphy's criticism is that DFID, which has an office in East Kilbride, is too focused on hitting targets for handing out aid instead of thinking about how to change the world.
Among his concerns is the department's treatment of the target to spend 0.7% of UK GDP on overseas aid, which he warns is starting to be seen as a result in itself, not a means to an end.
A DFID spokesman said that NGOs and development agencies around the world "acknowledge this government's leadership on development".