Welfare recipients who flog their wares on eBay have been warned - the department that manages Centrelink is after you.

The Department of Human services wants to recover more than $1.7 million in debt it has identified from people getting benefits who fail to declare their income from the website.

It has investigated 95 cases since the "eBay project" - an anti-fraud program that allows it to match its data with eBay's - started in September 2011.

In data released to the Senate, the department said 87 debts were recovered but couldn't say how much.

But it has vowed to keep working with eBay to track more would-be welfare cash-converters.