WASHINGTON, DC, May 17 -- The United States has almost run out of available visas for foreign workers with high-tech skills, despite Congress' nearly doubling the number available this year. The Immigration and Naturalization Service says it will exhaust its annual allotment of the visas in June, four months before the end of the federal government's fiscal year.The visas are earmarked for those in technical professions, such as engineers, scientists, doctors and computer specialists. Many companies claim they depend on foreign workers to compensate for a shortage of skilled Americans. Labor representatives, however, say American companies favor foreign workers because they can pay them lower wages. The INS is unable to explain the increased demand causing the current visa shortage.