WASHINGTON (AP) — The Justice Department is announcing a new phase in efforts to combat human trafficking.

Attorney General Loretta Lynch says federal officials are looking for cities to participate in the next phase of a program aimed at streamlining trafficking investigations and prosecutions.

The idea is to build on an initiative from 2011 that officials say has resulted in more trafficking cases and convictions.

The cities selected for the first phase were Atlanta; El Paso, Texas; Kansas City, Missouri; Memphis, Tennessee; Miami; and Los Angeles.

The Justice Department says up to six districts will be picked for the next phase, which will feature increased advanced training and streamlined coordination. Teams will be compromised of federal prosecutors and investigators representing different agencies.

Lynch said the program's results so far were "extraordinary."