BOSTON• 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 sitcom Full House (1987 to 1995), her husband and nine other parents now face the charge of conspiracy to commit federal bribery on top of previous charges, prosecutors said.

Loughlin and designer Mossimo Giannulli are accused of paying a US$500,000 (S$681,640) bribe so that their two daughters could gain entrance into a prestigious Californian university.

Prosecutors say they paid the money in 2016 and 2017 so that the girls could gain entrance to the University of Southern California 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.

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

United States 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, whom the authorities say was paid about US$25 million to bribe coaches and university administrators, has pleaded guilty and is cooperating with authorities.

Desperate Housewives (2004 to 2012) actress Felicity Huffman was sentenced last month to two weeks in jail after admitting to paying US$15,000 to boost her daughter's SAT college entrance examination score.

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

AGENCE FRANCE-PRESSE