SEOUL, South Korea — Samsung on Saturday urged consumers worldwide to stop using Galaxy Note 7 smartphones immediately and exchange them as soon as possible, as more reports of the phones catching fire emerged even after a global recall by the company.

The call from the South Korean company, the world’s largest maker of smartphones, came after the United States authorities urged users to switch the Galaxy Note 7 off and not to use or charge it during flights. Several airlines around the world asked travelers not to switch on the smartphone or put it in checked baggage, and some carriers banned the phone on flights.

In a statement posted on Saturday on its website, Samsung asked users around the world to “immediately” return their existing Galaxy Note 7 and get a replacement.

“We are asking users to power down their Galaxy Note 7s and exchange them as soon as possible,” said Koh Dong-jin, the president of mobile communication for Samsung. “We are expediting replacement devices so that they can be provided through the exchange program as conveniently as possible.”