One of the men who accused Cardinal George Pell of sex offences has died.

Damian Dignan died in Victoria on Saturday after a long illness.

Mr Dignan accused Cardinal Pell of historic sex offences in an explosive interview on the ABC’s 7.30 program in March 2016.

He claimed the 76-year-old touched his genitals in a pool in Ballarat.

The allegations spurred on Victoria Police to reveal Australia’s highest-ranking Catholic was a subject of an investigation by the Sano Taskforce, which investigates claims of sex abuse within Victorian churches.

Cardinal Pell has since been charged with multiple historic sexual offences and will face a four-week committal hearing in March.

He has always maintained his innocence and said he would “vigorously” defend the charges.

There are now concerns, that without Mr Dignan, prosecutors may be forced to change the structure of their case.

“It’s not an unreasonable quote to say that prosecutors could have a more difficult task now, yes,” former chief Victorian magistrate and crown prosecutor Nicholas Papas told The Australian.

“Normally it requires that the person who has given evidence to be there, and so normally it would be the case that without them there, the prosecution can’t proceed ... but you can’t be absolutely sure.

“It’s not unusual for witnesses to die and there are provisions in various bits of legislation that allow for statements to be tendered.

“If they’ve given evidence at a commission or they’ve previously submitted sworn evidence, that might leave open an opportunity for the prosecution to rely on those statements, but you would normally say that (having an accuser pass away) is the end of a prosecution,” Mr Papas said.

Victorian police have not said if Mr Dingan’s death would affect the case against Cardinal Pell.

© Nine Digital Pty Ltd 2018