AceShowbiz - Lori Loughlin's stepson has raised concerns about the mental and physical health of his imprisoned father Mossimo Giannulli, revealing the fashion designer has been "locked in solitary confinement" for a month.

The disgraced actress and her husband were both sentenced to prison time, community service, and fined in August (20) after pleading guilty to offering up bribes to help their two daughters score places at the University of Southern California (USC).

Loughlin began her two-month sentence on 30 October while Giannulli surrendered to authorities to start his five-month punishment at The Federal Correctional Institution, Lompoc in California on 19 November.

However, according to Gianni Giannulli, Mossimo's son from a prior relationship, his dad has been subjected to harsh conditions behind bars, where he was "supposed to serve his time in a 'minimum security camp.' "

"Instead, (Mossimo) has been locked in solitary confinement in a quarantine (sic) in the MEDIUM security prison in a cell for one full month today," Gianni posted on his Instagram Story timeline. "Only let out every 3 days for a few moments to shower (sic)."

"The mental and physical damage being done from such isolation and treatment is wrong."

Gianni goes on to claim his father could face at least 20 more days in isolation.

Prison officials have declined to comment on Mossimo's cell status although keeping inmates in isolation hasn't been unusual during the COVID-19 pandemic, as authorities try to prevent the spread of the virus.

Former "Fuller House" star Loughlin was in isolation for 14 days towards the beginning of her prison stint, but she is expected to be released next week, just before Christmas.