Mexican authorities have located three bodies in the state of Baja California where one American and two Australian tourists were reported missing, the local prosecutor's office has said in a statement.

Australian brothers Callum, 33, and Jake Robinson, 30, and American Carter Rhoad, 30, were last seen on April 27, the Baja California state prosecutor's office previously announced. It referred to the missing American as Jack Carter Rhoad.

The state prosecutors office did not say whether the bodies were those of the three foreigners, but said the bodies were discovered during the search for the missing men. It also announced that three people who were being questioned in the case of the missing men had been arrested and charged.

"Three bodies were found south of the city of Ensenada, and they were recovered in coordination with other authorities during a specialised operation because they were found in a zone of difficult access," the office said in a statement.

The site where the bodies were discovered near the township of Santo Tomás was near the remote seaside area where the missing men's tents and truck were found Thursday on a remote stretch of coast.

Forensic tests on the remains will be conducted by a state laboratory which will allow for positive identification of the bodies, the prosecutor's office said in its statement.

Investigators continue to search the rugged area where the bodies were found for additional evidence, the statement added.

The three men were on vacation surfing near the popular tourist town of Ensenada, about 90 minutes south of the US-Mexico border. The men went missing Saturday. They did not show up at their planned accommodations over the weekend.

The US State Department said: "We are aware of those reports (of bodies) and are closely monitoring the situation. At this time we have no further comment."

Baja California prosecutors had said Thursday that they were questioning three people in the case. On Friday, the office said the three had been arrested and charged with a crime equivalent to kidnapping. It was unclear if they might face more charges.

Tents were found in the area where the missing men were last seen, said Ibarra, adding that they were formally reported missing days after their actual disappearance. María Elena Andrade Ramírez, the chief state prosecutor, said evidence found along with the abandoned tents was linked to the three people being questioned.

A burnt white pickup truck was also found in the area, authorities said.

Baja California is one of Mexico's most violent states, although the Ensenada area is considered safer. The US State Department advises Americans to reconsider travel to the state due to crime and kidnapping.

Asked about the discovery of the bodies, a US State Department spokesperson said: "We are aware of those reports and are closely monitoring the situation."

A spokesperson for Australia's foreign ministry said their embassy in Mexico was working closely with Mexican authorities and the Australian Federal Police. 

"A working team (of investigators) is at the site where they were last seen, where tents and other evidence was found that could be linked to these three people we have under investigation," Andrade Ramírez said Thursday. "There is a lot of important information that we can't make public."

"The Department of Foreign Affairs and Trade recognises this is a very distressing time for the family and is in regular contact with them to provide support."

On Wednesday, the missing Australians' mother, Debra Robinson, posted on a local community Facebook page an appeal for help in finding her sons. Robinson said Callum and Jake had not been heard from since April 27. They had booked accommodations in the nearby city of Rosarito.

Robinson said one of her sons, Callum, was diabetic. She also mentioned that the American who was with them was named Jack Carter Rhoad, but the US Embassy in Mexico City did not immediately confirm that. The US State Department said it was aware of reports a US citizen missing in Baja, but gave no further details.

Andrade Ramírez said her office was in contact with Australian and US officials. But she suggested he time that had passed might make it harder to find the missing trio.

"Unfortunately, it wasn't until the last few days that they were reported missing. So, that meant that important hours or time was lost," she said.

In 2015, two Australian surfers, Adam Coleman and Dean Lucas, were killed in western Sinaloa state, across the Gulf of California — also known as the Sea of Cortez — from the Baja peninsula. Authorities said they were victims of highway bandits. Three suspects were arrested in that case.