President Barack Obama warned Americans on Thursday who have not prepared for the June 12 transition to digital television that their TVs could go dark if they do not get a converter box soon.

I want to be clear: there will not be another delay. I urge everyone who is not yet prepared to act today, so you don't lose important news and emergency information on June 12, Obama said in a statement.

Congress originally mandated the nation's nearly 1,800 full-power television stations to switch to digital signals from analog on February 17, and about one-third did so at the time.

But fearing that as many as 20 million mostly poor, elderly and rural households were not ready, lawmakers voted early this year to postpone the transition almost four months.

The number of households unprepared for digital television has been cut in half. Still, some people are not ready, said Obama, who has been traveling in the Middle East.

I encourage all Americans who are prepared to talk to their friends, family, and neighbors to make sure they get ready before it's too late, Obama said.

The switch is intended to free up airwaves for broadband and enhanced emergency communications for police, firefighters and other first responders.

A converter box for TVs that now rely on an antenna to receive a broadcast signal costs between $40 and $80.

The Commerce Department offers $40 coupons through its website at www.dtv2009.gov. It warns consumers who apply now that they may not receive a coupon in time.

(Reporting by Doug Palmer; Editing by Peter Cooney)