US law enforcement said Sunday a body found in a US national forest in Wyoming, where a search was underway for Gabrielle "Gabby" Petito, matches the description of the missing woman, whose disappearance has gripped the country.

American authorities launched a massive search for 22-year-old Petito when her family filed a missing person report on September 11, after she mysteriously vanished during a road trip with her boyfriend.

After a body was found in the main search area in Wyoming on Sunday, the Federal Bureau of Investigation said the remains matched the description of Petito.

"Earlier today human remains were discovered consistent with the description of Gabrielle 'Gabby' Petito," FBI agent Charles Jones told a press conference.

"Full forensic identification has not been completed to confirm 100 percent that we found Gabby, but her family has been notified of this discovery," he said, adding that cause of death had not been determined.

The FBI and other law enforcement had been searching for Petito in a national forest in the western state of Wyoming, where the couple was when Petito last communicated with her parents in late August, according to her family.

"I would like to extend Sincere and heartfelt condolences to Gabby's family," Jones added.

"We ask that you all respect their privacy as they mourn the loss of their daughter."

Petito quit her job and packed her life into a camper van for a cross-country adventure in July with her boyfriend Brian Laundrie, 23, documenting their journey in a stream of idyllic-seeming Instagram posts.

But more than two weeks ago, Laundrie returned to his home in North Port, Florida alone in Petito's van. Ten days later, her family filed a missing person report.

Laundrie was declared a "person of interest" in the case and declined to cooperate with police.

The mystery deepened after Laundrie also went missing.

On Friday, North Port police said Laundrie's parents claimed they had not seen their son for several days.

This August 12, 2021, still image from a police bodycam released by the Moab City Police Department in Utah, shows Gabrielle Petito speaking with police as they responded to an altercation between Petito and her boyfriend, Brian Laundrie
This August 12, 2021, still image from a police bodycam released by the Moab City Police Department in Utah, shows Gabrielle Petito speaking with police as they responded to an altercation between Petito and her boyfriend, Brian Laundrie Moab City Police Department / Handout

In a statement, the police underscored that while he was a person of interest, "he is not wanted for a crime."

In the wake of the FBI announcement on Sunday, the North Port police tweeted the force was "saddened and heartbroken" by the news.

"Our focus from the start, along with the FBI, and national partners, has been to bring (Petito) home. We will continue to work with the FBI in the search for more answers."

The couple embarked on their journey across the US from New York on the East Coast, posting photos of magnificent views of the American West and the two of them smiling happily next to their small white van.

In one YouTube video published during their trip, Petito and Laundrie are shown kissing tenderly, enjoying a sunset together and strolling on a beach.

However, in August, police in Utah responded to a domestic violence report involving Petito and Laundrie.

Police body cam footage published by US media shows a distraught Petito saying she had had an altercation with Laundrie.

Speaking to a police officer after their van was pulled over, Petito is seen crying and saying she struggles with mental health problems.

Petito said she slapped Laundrie after an argument, but added that she meant no harm.

"We've just been fighting this morning, some personal issues," she said.

"He wouldn't let me in the car before... he told me I needed to calm down."

Laundrie told police that Petito tried to get the van keys from him and he pushed her before she hit him with her phone.

The police officer decided no charges would be brought but ordered the couple to spend a night apart to calm down.

News of Petito's disappearance sparked a flood of calls to help find her on social media.

Her father, Joe Petito, appealed for anyone with information on her whereabouts to contact the authorities, adding that an anonymous tip line had been set up.

Jones on Sunday said public response for a request for tips had been "remarkable," and that investigators continue to seek information related to Petito and Laundrie.