Actress Lori Loughlin was slapped with an additional charge related to America's wide-ranging college admissions scandal on Tuesday, increasing the likelihood that she could serve time in prison.

The star of 1980s-90s sitcom "Full House," her husband and nine other parents now face the charge of conspiracy to commit federal programs bribery on top of previous charges, prosecutors said.

Loughlin and designer Mossimo Giannulli are accused of paying a $500,000 bribe so that their two daughters could gain entrance into a prestigious Californian university.

Prosecutors say they paid the money in 2016 and 2017 to that the girls could gain entrance to the University of Southern California (USC) by posing as members of the rowing team.

They have denied conspiracy to commit mail fraud and money laundering, charges that can carry penalties of more than 20 years in prison.

Lori Loughlin and husband Mossimo Giannulli "Full House" star Lori Loughlin (C) and her husband, designer Mossimo Giannulli (L), were among 50 people indicted in the wide-ranging college bribery scandal. Photo: AFP/Joseph Prezioso

If convicted, the extra charge leveled Tuesday could see the parents get a lengthier sentences. Prosecutors sometimes add extra charges to pressure defendants into changing their pleas.

US Attorney for Massachusetts Andrew Lelling said the new indictment would further prosecutors' efforts to hold the defendants "fully accountable."

The ringleader behind the college admissions scam, William "Rick" Singer, who authorities say was paid about $25 million to bribe coaches and university administrators, has pleaded guilty and is cooperating with authorities.

"Desperate Housewives" actress Felicity Huffman was sentenced in September to two weeks in jail after admitting paying $15,000 to boost her daughter's SAT college entrance exam score.

Huffman was the first parent to be sentenced among 50 people indicted in the elaborate and scam to help children of the elite secure places in top US colleges.

Other universities targeted in the scam include Stanford, Yale, Georgetown and UCLA. None of the schools or the students have been charged in the case.