Actor Felicity Huffman and 13 other people have agreed to plead guilty to participating in what prosecutors have called the largest college admissions scam uncovered in US history.

Key points: Huffman has issued a statement apologising for her actions

Huffman has issued a statement apologising for her actions Actress Lori Loughlin is not part of the group entering guilty pleas

Actress Lori Loughlin is not part of the group entering guilty pleas Huffman allegedly had her daughter's test answers altered

The 14 are among 50 people, including wealthy parents and college team coaches, accused by federal prosecutors in Boston of engaging in schemes that involved cheating on college entrance exams and paying $25 million in bribes to secure their children admission at well-known universities.

Streaming giant Netflix announced it was delaying the release of the film When They See Us, which stars Huffman, until later next month after news of the plea deal broke.

Huffman, who starred in Desperate Housewives, was among 33 parents charged in March with participating in the scheme designed to get children into universities including Yale, Georgetown and the University of Southern California.

Prosecutors on Monday (local time), as part of a plea deal, agreed to recommend a prison term at the "low end" of the four to 10 months Huffman faces under federal sentencing guidelines.

She also agreed to pay a $20,000 fine and restitution.

Huffman, who is married to the actor William H. Macy, said in a statement she was "ashamed of the pain I have caused my daughter, my family, my friends, my colleagues and the educational community".

"My daughter knew absolutely nothing about my actions, and in my misguided and profoundly wrong way, I have betrayed her," the former best actress Oscar nominee said.

Macy was not charged and authorities have not made any comment.

All of the parents will have to return to Boston to enter formal guilty pleas, but no new court dates were set.

Felicity Huffman (left) and actress Lori Loughlin (right) are the most high profile people to be charged. ( Reuters )

Answers secretly corrected on SAT tests

Authorities said the scheme was overseen by California college admissions consultant William "Rick" Singer, who has pleaded guilty to facilitating the cheating scam and bribing coaches to present the parents' children as fake athletic recruits.

Prosecutors said Huffman, 56, made a $15,000 contribution to Singer's foundation in exchange for having an associate of Singer's in 2017 secretly correct her daughter's answers on a college entrance exam at a test centre Singer controlled.

Fellow actress Lori Loughlin, who featured on the sitcom Full House, and her fashion designer husband, Mossimo Giannulli, are charged with paying $500,000 in bribes to get their two daughters admitted to the University of Southern California as crew recruits, even though neither participated in the sport.

They were not among those who agreed to plead guilty, and they have not publicly addressed the allegations.

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