The Regional Assistance Mission to Solomon Islands, or RAMSI, says while it is difficult to tackle corruption it is hopeful of making progress.
The mission's deputy head, Peter Noble, says serious top level corruption is a phenomenon of the last decade which worsened through the recent crisis.
A recent report by Transparency International says RAMSI has yet to tackle what it describes as big fish.
Mr Noble says RAMSI is involved a broad programme to fight all forms of corruption which he says was fostered by economic problems.
"I'm reasonably optimistic, and I think a lot comes from this lack of opportunity. When you have nothing, of course you are going to ask for things. And if you have absolutely nothing you take things by any means you can get them. Those are the huge pressures that so many people in the Solomons are under."
Peter Noble of RAMSI