Image copyright PA Image caption US officials say the suspects posed as students to take college entrance exams

The US Department of Justice has charged 15 Chinese nationals with developing a scheme to have imposters take university entrance exams.

Prosecutors said suspects used fake passports to trick administrators into allowing people other than legitimate test takers to sit the exams.

The scheme took place between 2011 and 2015 mostly in western Pennsylvania, authorities said.

Those charged could face up to 20 years in prison if convicted.

The defendants, both male and female, range in age from 19 to 26, and are currently living in several cities - including Blacksburg, Virginia, and Boston, Massachusetts - where major universities are located, the Reuters news agency reported.

The counterfeit test takers sat for the Scholastic Aptitude Test (SAT) - a major university entrance exam in the US - as well as the Test of English as a Foreign Language (Toefl) and the Graduate Record Examination (GRE), the Justice Department said.

Image copyright Getty Images Image caption The SAT is a major university entrance exam in the US

The scheme's beneficiaries "fraudulently obtained admissions to American institutions of higher education," said US Attorney for the Western District of Pennsylvania David Hickton.

The prosecutor said that the students also cheated student visa requirements by using counterfeit Chinese passports.

The Pittsburgh Post-Gazette reported that 24-year-old Siyuan Zhao, who resides in Massachusetts, has been detained. Han Tong, 24, of Pittsburgh, Pennsylvania, who is considered the primary defendant, and 10 others will receive an order to appear in court.

The newspaper reports that three others are currently in China, and their names have been redacted from court documents.

Special Agent in Charge John Kelleghan for Homeland Security Investigations of Philadelphia said: "These students were not only cheating their way into the university, they were also cheating their way through our nation's immigration system".

The defendants could face up to 20 years in prison, a fine of $250,000 (£163,000) or both for each of the wire and mail fraud counts they face. Additionally, they face five years on top that for the conspiracy charges.