Bill Gates, the world's richest man and chairman of Micro­soft, warned the nation's lawmakers Wednesday that restricting the number of skilled workers allowed into the U.S. will put the country at risk of losing its competitive and technological edge.

"The U.S. cannot maintain its economic leadership unless our work force consists of people who have the knowledge and skills needed to drive innovation," Gates told the Senate committee that oversees labor and education issues.

His comments echo other leaders in the technology industry who warn that immigration policies governed by terrorism fears — magnified by declining math and science programs in the nation's schools — could quickly create a technology gap.

“It makes no sense to tell well-trained, highly skilled individuals, many of whom are educated at our top colleges and universities, that the United States does not welcome or value them,” Gates said. “America will find it infinitely more difficult to maintain its technological leadership if it shuts out the very people who are most able to help us compete.”

Gates said that other countries — primarily India and China — are taking advantage of restrictive U.S. policies.

“Our lost opportunities are their gains,” he said. “I personally witness the ill effects of these policies on an almost daily basis at Microsoft.”

Gates said the nation's economy depends on keeping the country's borders open to highly skilled workers, especially those with a science or engineering background. Federal law provides 65,000 H1-B visas for scientists, engineers, computer programmers and other professionals every budget year. High-tech and other employers say that's not enough.

"Even though it may not be realistic, I don't think there should be any limit," Gates said, adding that Microsoft hasn't been able to fill approximately 3,000 technical jobs in the United States because of a shortage of skilled workers.

Gates, whose charitable foundation has given away more than $3 billion since 1999 for educational programs and scholarships, also noted that about 30 percent of U.S. ninth-graders fail to graduate on time.

"As a nation, we should start with this goal: Every child in the United States graduating from high school," he said.

Gates also challenged lawmakers to push for higher educational standards and to make more challenging coursework available to students.

A federal study released last month showed about a third of high schoolers fail to take a standard-level curriculum, which is defined as including at least four credits of English and three credits each of social studies, math and science.

Gates also called on lawmakers to give more resources and attention to improving the teaching of math and science — knowledge essential to many of today's jobs. Another recent federal study found 40 percent of high school seniors failed to perform at the basic level on a national math test. On a national science test, half of 12th-graders didn't show basic skills.

Legislation moving through the Senate, backed by Democratic and Republican leaders, seeks to get more people to become math and science teachers and would improve training for them. The bill also seeks to get more highly trained teachers in poor schools and would offer grants to states to better align their teaching with what kids should know to succeed at a job or in college.

Sen. Edward M. Kennedy, D-Mass., chairman of the Committee on Health, Education, Labor and Pensions, said the issue would be addressed when Congress takes up broad immigration reform legislation this session. President Bush has expressed support for raising the visa cap.

The Associated Press and Financial Times contributed to this report.