Tens of thousands of Massachusetts immigrants may find out sooner rather than later about the status of their naturalization requests.

Pointing to progress in processing millions of naturalization applications nationally, U.S. immigration officials announced Tuesday that the average time of processing is expected to drop six to eight months by the end of September.

The announcement, at a press conference in Government Center's JFK Federal Building, came as Congressional aides from across the region flocked to Boston to quiz the officials on concerns ranging from narrow constituent issues to broad visa concerns.

To be eligible for naturalization - that is, legal citizenship - applicants must meet one of three criteria: be U.S. residents over 18 years old who have resided in America for at least five years; be over 18, have resided in America for at least three years and be married to a U.S. citizen for three years; or have served honorably in the U.S. military.

Federal officials attributed the sharp decrease in naturalization processing time - from 16-18 months down to 10-12 months - to increased hiring at the U.S. Citizenship and Immigration Services agency and expanded work hours.

"People have worked overtime. The employees have worked weekends," said CIS Acting Director Jonathan Scharfen. "We haven't cut corners."

In addition, a fee increase implemented July 31, 2007 has helped lead to a slowdown in applications, he noted.

"I know that the fee rules were not without controversy," he said. "That was a heavy lift for a lot of people."

Processing slowed significantly, officials said, in fiscal 2007, when the agency received 1.4 million naturalization requests, about double the previous fiscal year.

Naturalization processing times vary from city to city. After much of the application backlog is cleared by the end of September, CIS officials expect the Boston office to process applications within 8.8 months, better than the national average, but higher than the agency's five-month target. Scharfen said he expects Boston to meet the five-month target with six months of the new federal fiscal year beginning Oct. 1. The Boston office, he said, was expected to process 32,000 applications in the next fiscal year.

A handful of cities are expected to meet the target at the end of next month, including Indianapolis, Sacramento, San Antonio and West Palm Beach. On the other hand, New York City, Miami, Charlotte, Hartford and Los Angeles are all expected to average 10 or more months to process naturalization applications.

Scharfen also vowed that CIS would work to stem delays in naturalization that have resulted from FBI name check requests. Such requests are required to vet all applicants for naturalization and have sometimes delayed the process for months.

"That's been a problem that's bedeviled our agency," he said. "The vast majority of people caught up in that process were good people."

In a Q & A session after the press conference, an aide to Maine Sen. Susan Collins sharply challenged Scharfen to inform "the ranking member" of the Committee on Homeland Security and Governmental Affairs when regulations regarding a seasonal worker immigration program would be developed.

After answering several other questions, Scharfen noted that it would require "an act of Congress" to increase caps on "employment-based visa programs." He said a problem of some of those visas going unused, a result of the complications of coordination among CIS, the State Department and the Department of Homeland Security, would not recur in the next fiscal year.

"This year, we will not leave visa numbers on the table," he said.

Citing repeated constituent calls, an aide to Sen. John Kerry requested that CIS better coordinate its websites so residents know where to send immigration forms.

Other concerns raised by attendees included the process by which the agency requests and maintains fingerprints and the rate at which the United States brings in refugees from around the world. Scharfen said he planned to travel to Baghdad to increase the "refugee stream" and that Nepal and Lebanon were also set to increase their refugee totals. He warned that disease outbreak or violent conflict often disrupt the agency's ability to receive refugees.

At the press conference, CIS officials also unveiled a revised naturalization test, updating the wording on dozens of questions about U.S. history, the Constitution and fundamental principles of American democracy.