"The move by Iran of the American hostages from Evin Prison to an expected house arrest is an important development," Genser said in a statement.
A second source familiar with the indirect U.S.-Iranian talks said it could be weeks before the U.S. citizens could leave Iran, saying September was a possible time frame.
Namazi, who in 2016 was convicted of espionage-related charges the United States has rejected as baseless, has been detained by Iran for more than seven years.
His father, Baquer, was allowed to leave Iran in October for medical treatment after being detained on similar charges also rejected by Washington.
Tahbaz was arrested in 2018 and sentenced to 10 years in prison for "assembly and collusion against Iran's national security" and working for the United States as a spy.
Persons:
Dado Ruvic, Tehran's, Siamak Namazi, Emad Shargi, Morad Tahbaz, Jared Genser, Genser, Adrienne Watson, Joe Biden, Baquer, Tahbaz, Shargi, Arshad Mohammed, Parisa Hafezi, Humeyra Pamuk, Jeff Mason, Jasper Ward, Dan Whitcomb, Mark Porter, Lisa Shumaker, Grant McCool
Organizations:
REUTERS, WASHINGTON, U.S, Iranian, Security, eventual, Democrat, Washington, Iran's, Thomson
Locations:
DUBAI, Iran, South Korea, United States, U.S, Washington, Tehran, Iraq, Lebanon, Yemen, Dubai