American students have fallen further behind their peers around the world in science and math, according to a report by the Program for International Student Assessment.
The results, released Tuesday, showed scores among high school students in many Asian countries are rising while American performance on the tests is mired in mediocrity.
"Among the 34 [Organization for Economic Cooperation and Development] countries, the United States performed below average in mathematics in 2012 and is ranked 26th (this is the best estimate, although the rank could be between 23 and 29 due to sampling and measurement error)," the report said. "Performance in reading and science are both close to the OECD average. The United States ranks 17 in reading, (range of ranks: 14 to 20) and 21 in science (range of ranks: 17 to 25). There has been no significant change in these performances over time."
The Obama administration said the disappointing test results should fuel a renewed focus on education.
"We must invest in early education, raise academic standards, make college affordable and do more to recruit and retain top-notch educators," said Education Secretary Arne Duncan.
Others said the scores indicate a low cultural emphasis on education in the United States.
"America tends to be much less academically oriented than other countries that have done well on these tests," said Neal McCluskey, associate director of the Center for Freedom at the Cato Institute.
Mr. McCluskey said the results point up the disconnect between spending and educational performance.
"Different analyses show there's really very little correlation between spending and testing scores," he said.
National educators and policymakers were disheartened.
"There's absolutely no reason we should settle for mediocrity, especially when it comes to our kids," said Michelle A. Rhee, founder of StudentsFirst and former chancellor of the District of Columbia Public Schools. "American students are capable of high achievement on the international stage, and there are just as many exceptional educators in our great nation, but our system has been failing them. While some bipartisan progress has been made to put in place student-centered reforms that are beginning to show results, far too many political and educational leaders are sitting still."
The international report said the U.S. has a higher percentage of students flunking the test than do most other countries and a smaller and "a below-average share of top performers."
Students in Shanghai, China's largest city, had the top scores in all subjects, and Singapore, South Korea, Japan and Hong Kong students weren't far behind. Even Vietnam, whose students participated for the first time, showed higher average scores in math and science than the United States.
"Americans have got a thousand reasons that one country after another is surpassing our achievement, and I have yet to find a good excuse," said Marc Tucker, president of the National Center on Education and the Economy.
About a half-million students in 65 nations and educational systems took part in the 2012 tests, which were coordinated by the Paris-based OECD.
• This article is based in part on wire service reports.