Contractors employed by Centrelink to scan the Facebook pages, Twitter streams and eBay accounts of customers have dredged up more than $2 million in fraud the Daily Telegraph reported.

The operations could nab a fraudster via a guileless 'Thank God It's Friday' Facebook post at the end of a work week from a recipient of unemployment benefits, or perhaps an uninhibited single posting voraciously about their solo life while claiming benefits for dependents they don't have.

In one case, a couple who claimed they were single to receive single payments were caught out by Centrelink's social media surveillance investigators when they announced on Twitter that they were in a relationship and expecting a baby, according to the Department of Human Services.

Centrelink contracted investigators have also nabbed $1.7 million in fraud by scanning the eBay online auction accounts of welfare recipients who were selling off assets without declaring the sale price as income.

The work is part of the Department's Taskforce Integrity operations launched in August 2015 to crackdown on fraud, and recoup the roughly $3 billion in overpayments to welfare recipients.

According to the Minister for Humans Services, Stuart Robert, the operations have lead to 3,072 compliance reviews,1,888 cases of overpayment and five arrests on warrants for failing to attend court for welfare fraud offences.

"While most people receiving welfare payments are honest and do the right thing, there is a small segment of the community who still think it is okay to cheat the system," Mr Robert said in a statement on Wednesday.

"Taskforce Integrity will continue to collaborate with its partner agencies to meet the challenges posed by welfare fraud and ensure those individuals who deliberately defraud the system are caught," he said.

In January 2015 the federal government announced that it had almost halved the amount it spent on covert surveillance to catch out welfare cheats.

At the time a department spokesperson said the reduction was in part due to the cost-effective method of checking a person's social media accounts.

The term "optical surveillance" was used to describe tailing people under suspicion of fraudulent activity, such as child support avoidance or income minimisation.

Private investigators said they were restricted to observing people in public places for what was termed "optical surveillance".

It is understood that social media surveillance would follow the same restrictions, with investigators scanning publicly available profiles only, without judicial warrants.