PHOENIX (AP) -- A new immigration fee schedule went into effect nationally Monday, boosting costs for applicants seeking permanent residency, naturalization or other services, in some cases by more than 100 percent.

Under the plan, which has been hotly contested by immigration rights advocates, fees go up by an average of 70 percent, the government said. The cost to apply for naturalized citizenship increased from $400 to $675. The application fee for a residency permit hops from around $300 to more than $1000.

US Citizenship and Immigration Services, the federal agency that deals with services to immigrants, said the fee increases are necessary to streamline their services and modernize infrastructure. The agency relies mostly on application fees for its operations and has been hampered by an inability to keep up with demand, officials said.

Officials project that the fee increases will nearly double USCIS's revenue, bringing in an additional $1 billion in the next fiscal year.

By fiscal year 2009 the agency hopes to reduce application processing times by about 20 percent.

"We are required to recover our costs and we have not been recovering our costs," said spokeswoman Marie Sebrechts, who added that many immigrants will be able to apply for special fee waivers.

But some immigrant rights advocates who have been fighting the fee increases since the government announced them earlier this year remain unconvinced.

"It raises the question of whether citizenship is being made inaccessible to people," said Kat Rodriguez, a coordinator with the Coalition de Derechos Humanos, in Tucson, Ariz. "Doing anything to make it harder for people to get citizenship is bad. These increases are not going to be any help to people who can't afford them."

Immigrants have raced to beat the increases, flooding USCIS with applications. About 135,000 people filed naturalization application in June compared with 71,288 in June 2006, according to government statistics. Sebrechts, however, said some of increases were the result of better services by the government, the high visibility of immigration issues and natural fluctuations.

Fifty-year-old Maria Medran of Phoenix, who came from Mexico to work about 20 years ago, applied for naturalization earlier this year and was sworn in as a citizen on July 4, said the fee increases have been a topic of conversation in the immigrant community.

"Many people have been talking about the money," she said at the ceremony. "For some people, it will be very hard."

Last year, 700,000 people were naturalized nationwide.