The Afghan government, increasingly at odds with Washington, is cracking down on advertisements that promote keeping U.S. troops in Afghanistan after 2014 and has already shut down a spot aired by the country's most widely watched broadcasters.
The commercials - some funded by a U.S. organisation - have drawn official criticism because they urge President Hamid Karzai to abandon his refusal to sign a security pact with the United States that would enable the troops to stay.
Broadcasters, which ran the spots for several weeks, came under investigation on grounds that their source of funding was unclear. All have pulled the advertisements off the air.
"We have launched an investigation into broadcasters to find out where they receive money from for such advertisements," Basir Azizi, a spokesman for the attorney general, told Reuters on Wednesday.
Despite Karzai's refusal to sign the Bilateral Security Agreement (BSA) unless several conditions were met, many Afghans are uncertain the army is able to fend off Taliban insurgents without help from the NATO-led ISAF coalition of troops.
The commercials often include interviews with rank-and-file Afghans calling on Karzai to sign the accord immediately.