Nearly one-third of Virginia’s public schools will not earn full accreditation this fall after reading and science scores dropped precipitously on state-mandated standardized tests, according to state education officials.

Officials estimate that 600 or more of the state’s approximately 1,800 schools could be “accredited with warning” next month — an exponential increase from five years ago, when 15 Virginia schools had the downgraded status.

Charles Pyle, spokesman for the state Department of Education, said as many as 250 schools will drop next month from “fully accredited” status, joining nearly 400 schools that had the lower status last year. Pyle said the state has increased the difficulty level of the annual Standards of Learnings (SOL) tests during the past three years and also has raised the bar for passing scores, leaving an increasing number of schools with substandard performance.

Pyle said the state raised the standards to help students get prepared for college and careers. Much of the country has adopted the national Common Core State Standards — which some argue are more rigorous than what some states taught their students — but Virginia is one of a few states that have not adopted them, opting instead to stick with an internal state system.

The dramatic increase in the number of schools dropping to “accredited with warning” status shows that “the increase in rigor in Virginia is real,” Pyle said. “They did it to benefit students to make it more likely that after 12 years of school a student will be ready for the first year of college without remediation or ready for employment in the job market. This is not easy. It’s not easy for students, and it’s not easy for teachers. But we believe, in the long run, this is in the best interest of students.”

Pyle said that schools with downgraded accreditation ratings are not penalized but are required to demonstrate plans for improvement. They also could qualify for additional resources.

A school that is newly facing warning status must submit to a state academic review that will include scrutiny of the school’s curriculum and instructional practices.

Schools that fail to meet full accreditation for four consecutive years must undergo a performance overhaul.

The state plans to announce school accreditation ratings next month, Pyle said, noting that officials expected many schools to see their accreditation level drop with this year’s tests.

“No one wants their neighborhood school accredited with warning,” Pyle said. “The state’s expectations have gone up. The bar has been raised significantly, and it’s going to be a multiyear process for students and schools to meet these higher expectations.”

Don Soifer, executive vice president of the Lexington Institute, an Arlington think tank, said the expected rise in schools accredited with warning warrants investigation.

“Without a doubt, that would be surprising to anybody that follows Virginia education,” said Soifer, who focuses on education policy and serves on the D.C. Public Charter School Board. “There’s never been a finding so drastic before. I would be surprised to see that the picture was so remarkably different from last year to this year.”

Last year, when the state gave 395 schools accreditation-with-warning status, it was the most since 2006, when 138 schools made the list, and was three times as high as the number in 2012. This year would have among the largest number of schools with a downgraded accreditation status since the state added SOL tests for sixth-, seventh- and eighth-graders to comply with No Child Left Behind, the federal education law.

New reading and science exams were introduced in Virginia last year, and a new math exam was first administered in 2012.

The new reading tests, which are administered online, cover more difficult content at earlier grade levels. On some interactive sections, students must examine a passage and insert correct punctuation.

Currently, 1,414 of the Virginia’s 1,827 schools — 77 percent — are fully accredited. Twenty-two percent are “accredited with warning.” Six schools have been denied accreditation.

Pyle said the status of many more schools probably will change next year.

“We have heard from a number of school divisions that scores on the reading tests are flat or down,” Pyle said.