Federal immigration authorities announced Tuesday that they are scrapping the current form for immigrants to apply for U.S. citizenship and replacing it in 90 days with a longer and more complex form that includes numerous new questions about the applicant’s links to terrorist groups, genocide, militias, prisons and military training.

Immigration officials said the changes were made partly to comply with new U.S. laws aimed at combating terrorism and child soldiers, and partly to make the form more efficient and easier to process. Although it is now 21 pages long instead of 10, the officials noted that considerable space is now taken up by thick bar codes on every page.

But a number of organizations that help U.S. green-card holders apply for citizenship complained that the changes would intimidate people into not applying, especially those with limited English who might have difficulty understanding the new questions. Some are long, complex and use numerous technical terms.

“At a time when we are all trying to naturalize as many people as possible, this will be a lot more laborious, time-consuming and discouraging for some people to fill out,” said Eric Cohen, executive director of the Immigrant Legal Resource Center in San Francisco. He said his group had suggested some questions be worded more clearly, but that immigration officials did not accept the advice.

“We are concerned that the new form will impact the vulnerable populations we serve,” said Jean Atkinson of the Catholic Legal Immigration Network based in Silver Spring, Md., which helps more than 10,000 low-income legal immigrants become citizens each year. “It’s safe to say the level of English it requires is significantly higher than the level required to pass the citizenship test.”

Since 2008, a yearly average of 750,000 green-card holders, formally known as permanent legal U.S. residents, have become naturalized U.S. citizens, according to U.S. government statistics. The great majority — about 100,000 per year — come from Mexico. Other countries of origin with more than 20,000 immigrants becoming citizens each year are China, India, the Philippines, El Salvador, Cuba and Vietnam.

Very few naturalized citizens come from countries associated with terrorism or child soldiers, but the Intelligence Reform and Terrorism Prevention Act of 2004 and the Child Soldier Prevention Act of 2007 require that U.S. officials “obtain sufficient evidence” to decide whether every foreign-born person in the U.S. may be barred from permanently immigrating.

The Obama administration, while increasing border-protection efforts and deporting record numbers of illegal immigrants, has been working to streamline and speed up the process of residency and citizenship for legal immigrants. Officials said the new application form would be easier and faster for them to process, and that none of the rules for eligibility have changed.

Immigration officials have given prospective citizens 90 days to apply using the current forms, and several legal assistance groups in the Washington area and across the country said they will be holding a series of workshops in the next three months to help green-card holders file their applications before May.