WASHINGTON-The first work permits and deportation deferrals have been mailed to young undocumented immigrants who applied under an Obama administration initiative that began last month.

More than 72,000 applications have been filed under the program, called Deferred Action for Childhood Arrivals, officials said. It's unclear how many have been approved.

"Following a thorough, individualized case review, (U.S. Citizenship and Immigration Services) has now begun notifying individuals of the determination on their deferral requests," Peter Boogaard, a spokesman for the Department of Homeland Security, said in a statement.

The first approval letters should begin arriving this week.

Since the program began Aug. 15, thousands of young illegal immigrants have attended workshops held by community organizations around the country to help families prepare the required paperwork.

Those who are approved will be permitted to work lawfully and granted a deferral of possible deportation for at least two years.

To qualify, applicants must prove they are younger than 31 and arrived in the U.S. before turning 16. They also must meet education or military requirements.

More than 1.2 million young undocumented immigrants may qualify for the program, according to an estimate by the Migration Policy Institute, a think tank.

Obama administration officials have said the program will aid law enforcement by allowing authorities to focus on deporting convicted criminals, instead of students and other noncriminals with strong family ties in the United States.

Last year, Immigration and Customs Enforcement expelled nearly 400,000 people, a record. More than half had criminal records or were repeat violators of immigration law.

House Judiciary Committee Chairman Lamar Smith, R-Texas, questioned the speed with which the first applications were reviewed.

"Such a quick turnaround for these amnesty applications raises serious concerns about fraud and a lack of thorough vetting," Smith said in a statement.

Smith also expressed concern that the flood of deferred action applications will lead to a backlog of applications from immigrants seeking to enter the country lawfully.

"It's appalling the administration has diverted resources from approving applications for those who have played by the rules to illegal immigrants," said Smith.

It costs $465 to apply for the program. Part of the fees collected will be used to hire additional USCIS staff to review the applications, collect fingerprints and conduct background checks.