The city is behind the rest of the state when it comes to students earning the relatively prestigious Regents high school diploma, an analysis of state graduation data shows.

Numbers obtained by The New York Sun yesterday also show that the rate of city students earning the Regents diploma has improved significantly over years past — after the state education department passed new regulations making it easier to earn one.

Sixty-eight percent of city students graduated at the Regents level last year, almost double the rate of past years, when it had been languishing at about a third. Outside of New York City, 87% of students earned the Regents diploma.

The percentage of city students graduating in four years with the less rigorous local diploma — 32% — was twice the percentage of graduates who earned a local diploma elsewhere in the state.

Chancellor Joel Klein last week hailed the release of overall graduation rate numbers showing the city gaining ground against the much higher graduation rate in the rest of the state. The city’s four-year graduation rate rose 6 percentage points in two years, to reach 50%, while the rest of state saw its graduation rate drop 2 percentage points during the same period, to 78%.

A Department of Education spokesman, David Cantor, said that like the overall graduation rate, the city is not “remotely satisfied” with the rate of students earning Regents diplomas, but that the trends are positive.

A former director of assessment for the city schools, Robert Tobias, said the rapid inflation of the number of students earning Regents diplomas as a result of the change in requirements is probably a good thing.

Unlike the previous system, all students must now take Regents examinations to graduate with a diploma, which is designated either a Regents or a local depending on the score, a requirement that Mr. Tobias said prevents students from being tracked into lower-level courses.

“It does encourage kids to take a college-level track,” Mr. Tobias, who now directs teaching and learning research at the Steinhardt School of Education, said. “In that sense, more kids are taking the more difficult subject matter.”

Students who took longer to graduate were much less likely to earn a Regents diploma, the data also showed. Less than a third of students who took six years to graduate and 58% of students graduating in five years earned a Regents diploma.

The change in requirements is a part of a decade-long effort by the state to strengthen graduation standards, according to a spokesman for the state education department, Tom Dunn.

“It’s a matter of consistency as well — to make sure that there’s … a consistent understanding of what a high school diploma is,” he said.

Now, to earn a Regents diploma, students must pass five Regents exams; before they had to pass eight. A local diploma now requires a score of at least 55 on five Regents exams. A new offering, the “advanced” Regents diploma, requires students to pass eight Regents exams with a score of 85 plus 22 credits.

The first school year the “advanced” diploma was offered, in 2004-05, the percentage of city students who earned one was 3%, according to a state report.

The city Department of Education declined to provide information about how many students earn the advanced Regents diploma in 2006 before an upcoming announcement of the city’s graduation rate, which is calculated differently than the state rate.

Mr. Tobias said the differentiation between the diplomas is often irrelevant for students who apply out of state, but baccalaureate programs at the City University of New York ask for a score of at least 75 on the Regents English and math tests, according to the university’s admissions Web site — 10 points higher than requirements for the regular Regents diploma.