The U.S. is driving away the world's best engineers and computer scientists by putting limits on H-1B visas and other immigrant worker programs, Microsoft Chairman Bill Gates told U.S. lawmakers Wednesday.

Gates repeated his past calls for more H-1B visas, the controversial program used by technology and other companies to hire foreign workers for up to six years. More than half of the students in computer science programs at top U.S. universities are from other countries, but a limit on H-1Bs means many of those students can't stay in the U.S. after they graduate, Gates told the House of Representatives Science and Technology Committee.

"We provide the world's best universities ... and the students are not allowed to stay and work in the country," Gates said. "The fact is, [other countries'] smartest people want to come here and that's a huge advantage to us, and in a sense, we're turning them away."

Gates' comments on immigrant worker programs and improving science and engineering education at U.S. high schools reflected his long-standing positions. Gates talked about the same issues before a Senate committee a year ago. Congress has set a limit of 85,000 H-1Bs each year, including 20,000 set aside for students with advanced degrees, and in recent years, those slots have been filled within days of the application period opening.

Many lawmakers agreed with Gates on H-1Bs and other issues, but some raised concerns about raising the H-1B limit. One recent study said 150,000 computer programmers in the U.S. have lost their jobs since 2000, said Representative Dana Rohrabacher, a California Republican.

"My view ... is there are people available," Rohrabacher said. "You just want to hire the top people from India and China."

Gates said Rohrabacher's numbers were based on a flawed study. Many large tech firms can't find enough qualified workers, he said.

Rohrabacher asked if H-1B workers were driving down U.S. wages or replacing "B and C students" from the U.S. Gates said no, citing a study released Monday by the pro-immigration think tank the National Foundation for American Policy, saying that for every H-1B position applied for, companies create an additional five jobs.

"The top people are going to be [paid] higher," Gates said. "It's just a question of what country they're working in."

Representative Laura Richardson, a California Democrat, challenged Microsoft and other tech companies to fund scholarships for science and engineering students with the money they use to recruit workers and apply for visas.