An innovative Manhattan high school lauded for its work with immigrants may be revamped soon, leaving adrift the kind of students it currently serves.

Liberty High School, in Chelsea, has for years been a one-year transitional school serving just-off-the-boat young people — some as old as 20 — with less than eighth-grade education. Now the Department of Education is planning to turn Liberty into a four-year institution for students who are no older than 18 and have eight or more years of schooling. The school’s superintendent says the change has been planned for years. But Liberty’s principal and several politicians are crying foul — they say schools administrators are pressing for change because they are misinterpreting the federal No Child Left Behind legislation.

Today Liberty has some 500 students from 60 countries. All are taught English, and bilingual classes are available for Chinese, Spanish and Polish speakers. Students learn survival skills such as how to talk on the phone and search for an apartment. After a year, they are steered to magnet high schools or GED programs.

Last summer, the Board of Ed told school officials that Liberty would become a four-year high school for immigrants younger than 19 with at least a middle-school education. All others will be sent to neighborhood high schools.

But high schools often deny admission to older applicants. When they do enroll, immigrants are frequently shunned by their more acculturated peers.

According to Liberty’s principal and union representatives, the superintendent said retooling was needed to comply with No Child. The state education department has explained that the No Child law requires schools to evaluate students’ progress — a difficult task for a one-year program.

But many politicos say state and federal officials have informed them that the No Child law does not require Liberty to change. Representative Jerrold Nadler, State Senator Tom Duane, Assemblymember Richard Gottfried and Councilmember Christine Quinn have all urged that Liberty be kept as is. In a letter sent to Chancellor Joel Klein last month, they called the school “unique” and “powerful,” and asserted that under No Child, it “can maintain its status as a one-year program.”

In explaining the proposed change at Liberty, said Nadler spokesperson Daryl Cochrane, schools officials cited No Child: “It was clearly the reason they were using, and no other.”

But Richard Organisciak, superintendent of alternative schools, said the plan to make Liberty a four-year school began five years ago — long before No Child became law.

Liberty principal Bruce Schnur said district officials had previously discussed the reorganization, but he resisted. Then, he adds, “Last year I was told that because of [No Child], we would have to change to a four-year school.”

There’s a chance Liberty will prevail: A meeting scheduled for Monday between school officials and the incoming district superintendent in charge of alternative schools will determine if some compromise can be reached.

“The teachers of this school feel a glimmer of hope,” said Carol Yankay, a Liberty teacher and United Federation of Teachers chapter leader, because Chancellor Klein’s department seems friendlier than its predecessor “to a more creative approach to educating newly arrived students.”