BETHESDA, Md. — U.S. regulators issued an official recall of Samsung’s Galaxy Note 7 phone on Thursday because of a risk of fire.

Samsung had voluntarily recalled the devices after a few dozen devices exploded or caught fire. That was out of about 2.5 million phones sold.

The U.S. Consumer Product Safety Commission is stepping in on a formal recall. Its chairman, Elliot Kaye, blasted Samsung for trying to do the recall on its own, saying that anyone who believes that to be adequate “needs to have more than their phone checked.”

Samsung promised replacement devices, but that was put on hold while regulators reviewed the situation. Kaye said customers will now be offered full refunds, not just replacement devices, if they choose. Note 7 owners need to contact Samsung and provide a number from the back of the phone to determine whether that unit is at risk.

Kaye said about 1 million devices are affected.

The recall comes at a crucial time for Samsung, as its rival Apple just announced its own latest versions of the iPhones, which go on sale Friday. The Note series is one of Samsung’s most expensive, and demand for the phone had been high.

In addition, the Department of Transportation is ordering airline passengers not to bring Samsung Galaxy Note 7 phones on planes unless they keep them turned off and don’t charge them during the flight.

Passengers also must disable all applications that could inadvertently activate the phone, like an alarm clock; protect the power switch to prevent the phone from being unintentionally turned on; and keep the device in a carry-on baggage or on their person, not in a checked bag.

Do you have a Galaxy Note 7 that was the subject of an official recall Thursday?

Here’s what to do if you own one of Samsung’s new smartphones. The U.S. safety watchdog, the Consumer Product Safety Commission, is urging consumers to exchange or return the device because of a risk of fire. The agency says there have been 92 reports of batteries overheating in the U.S. That includes 26 reports of burns and 55 reports of property damage, including to cars and a garage.

WHO IS AFFECTED?

The Consumer Product Safety Commission says the recall covers about 1 million Note 7s sold in the U.S. through Sept. 15.

HOW DO I CONFIRM THAT MY PHONE IS PART OF THE RECALL?

Look for an IMEI number on the back of the phone or on the phone’s packaging. You can also find it in the phone’s settings by going to “About Phone” or “General Management” and then hitting “Status.” Enter that number at http://samsung.com/us/note7recall or call Samsung’s recall hotline at 1-844-365-6197. U.S. officials say about 97 percent of Note 7s sold in the U.S. are affected.

WHAT ARE MY OPTIONS?

You can ask for a replacement or a full refund. For replacements, consumers can choose another Note 7 or a Galaxy S7 or S7 Edge, with a refund of the price difference. Consumers who bought the phone through a wireless carrier or retailer such as Best Buy should contact the merchant directly. Those who bought it directly from Samsung should contact the company.

Online and phone contact information for individual carriers, retailers and Samsung is available at http://samsung.com/us/note7recall.

MORE INFORMATION

Check out http://www.cpsc.gov/en/Recalls/2016/Samsung-Recalls-Galaxy-Note7-Smartphones.