The federal government has pursued the estates of up hundreds of dead people flagged as owing money under its much criticised robo-debt program.

The Department of Human Services, which controls Centrelink, has been using an algorithm to examine welfare payments and determine if people have been overpaid or collecting money they’re not entitled too.

In July, Government Services Minister Stuart Robert was forced to apologise after it was revealed a mother had been contacted by Centrelink over a perceived debt owed by her son, a disability pensioner who had died six months earlier.

“In the vast majority of times, compassion will step in and the debt will be wiped,” Mr Robert told Parliament.

“In this particular case, because of the size of the debt being both uneconomical to recover as well as the length of time, the department should have simply waived the debt.

“They didn’t, my department was wrong, I apologise for it.”

At a Senate hearing on Wednesday night, a committee heard there had been 515 instances of the estates of dead Centrelink clients being pursued to try to recover debts.

In 73 of these cases, debts were recovered. A further 442 were written off, the committee heard.

Liberal senator and Social Services Minister Anne Ruston told the committee “this can occur for a range of reasons, for example, where the department was not aware that the person was deceased, a delay in processing, a manual staff error, or a combination of these factors”.

Recipients of robo-debt letters are presumed guilty and must prove their innocence. But the government has admitted more than a quarter of debt notices sent have been wrong.

In September, the government said the robo-debt program was expected to cost more than $500 million over the next three years – and return $2 billion to the federal budget.

Centrelink has said it expects to run another 1.6 million robo-debt reviews in that time, despite calls to scrap the controversial welfare compliance program.

However, the program also faces several legal challenges. Two people who have already taken legal action have had their debts wiped, while Labor is supporting a class action against robo-debt.

It is also the subject of a Senate inquiry.

-with AAP