For the first time since the city imposed a hiring freeze two years ago, the number of teachers entering the classroom from alternative certification programs has risen.

While some senior teachers worry about finding positions, two prominent organizations, Teach For America and New York City’s Teaching Fellows, are contributing hundreds of new teachers to the city’s teaching force. The organizations estimate that they will bring about 800 new teachers into classrooms this fall.

That would be 25 percent more than last year, when the groups brought on just under 650 new teachers, about 2,000 less than in 2006.

The dropoff began in 2009, when the Department of Education enacted restrictions limiting most hiring to teachers who were already in the system. The policy severely curtailed recruitment plans for TFA and Teaching Fellows and in a matter of two years, both were producing just a few hundred teachers per year. Most of those teachers worked in shortage areas, such as science and special education.

Now, as the city has eased some longstanding hiring restrictions in new subjects, those numbers are inching back up in response to demand.

Teach For America admitted 335 members this year, a 50 percent increase from last year. For the second straight year, a majority of those teachers – about 180 – will work in charter schools. As many as 145 could end up in district schools, said New York TFA executive director Jeff Li. A small group will also be placed in non-profit organizations that support early childhood education.

Li attributed the increase to demand from new and expanding charter schools and in high-need subject areas in district schools.

Teaching Fellows, which doesn’t place teachers in charter schools, also increased its enrollment, but by less — from 425 to 455.

Despite the restrictions, the DOE still  hired roughly 3000 new teachers last year, according to a spokeswoman. It also lost about 2,600 teachers through attrition, according to a report from the Independent Budget Office, and projects losing 2,600 more this year.