US Southern Command said the vessels were linked to drug-trafficking operations and acted as floating resupply stations in international waters, while the fishermen disputed the account. Ecuador’s Permanent Committee for the Defence of Human Rights filed a habeas corpus petition on their behalf. The judge also ordered Ecuador’s Foreign Ministry to seek explanations from the US Embassy and called for a search for fishermen still missing after the operations.

Footage filmed on Sunday shows the ambulance belonging to Kimbiri Hospital in the Valley of the Apurimac, Ene and Mantaro Rivers (VRAEM), one of Peru's main coca-growing regions. Investigators said the vehicle was being used to transport narcotics concealed inside a hidden compartment.

"Personnel from [Grupo] Terna and this region's intelligence had information about the transport of this illicit merchandise in an ambulance from Kimbiri Hospital, Cusco, to the Ayacucho Regional Hospital, carrying a minor who had suffered a traffic accident," said Ayacucho police chief Arturo Valverde.

According to Valverde, officers found the drugs "in a hidden compartment, in the part where the air conditioning is, at the level of the stretcher," where they recovered 13 black packages containing 69 parcels of cocaine hydrochloride marked with a dolphin logo.

"This package of drugs has different values and abroad, due to its purity, it is worth approximately 30,000 dollars per package in Europe," he specified.

The operation was carried out by Grupo Terna officers and the Directorate of Intelligence outside the Ayacucho Regional Hospital in the district of Andrés Avelino Cáceres Dorregaray after the ambulance had dropped off a patient.

Police arrested the driver, Rubén Sáenz Vega, 38, and nurse Johans León Gutiérrez, 40.

Authorities believe the shipment belonged to the alleged trafficking group "La Cruz Blanca", which is accused of using the ambulance as a front to transport cocaine from the VRAEM to other parts of Peru.

The case has been handed to the Huamanga Provincial Specialised Prosecutor's Office for Illicit Drug Trafficking, which is leading the investigation.

On Wednesday, officers from the National Drug Law Enforcement Agency (NDLEA) dismantled the makeshift facility after a court approved its demolition during an ongoing drug trafficking trial involving three Mexican nationals.

AFP visited the site with NDLEA officers as a local welder and carpenter dismantled the cauldrons and filtration equipment used to manufacture methamphetamine.

The laboratory occupied about an acre of forest land between the villages of Abidagba and Iroto.

The court ordered the site to be dismantled because of the environmental risks posed by the chemicals used in the production process.

Patricia Afolabi, the NDLEA's director of forensics, said the decision was taken to prevent groundwater and air pollution .

When AFP visited, barrels containing chemicals and partially processed methamphetamine remained inside the shed, with strong fumes still filling the air.

The laboratory was raided in May, when authorities arrested 10 suspects, including three Mexican nationals and seven Nigerians. Officers also searched two residential properties in an upscale Lagos neighbourhood, seizing methamphetamine and precursor chemicals worth an estimated $360 million.

The criminal case remains before the courts in Lagos.

The discovery has raised concerns over the presence of Mexican drug cartels in Nigeria.

"About our readiness to combat the cartel... yes, we are ready," NDLEA Deputy Commander of Narcotics James Taalba told AFP.

"We have people who are capable of curtailing such a situation."

West Africa has increasingly become a transit route for cocaine shipments moving from South America to Europe. Authorities also say methamphetamine production has expanded in the region as foreign criminal groups bring their expertise to local operations.

A 2019 report by the Institute for Security Studies found that methamphetamine seizures and laboratory raids in Nigeria have increased since around 2011.

Another Mexican national was arrested in a separate methamphetamine operation in Oyo State in June.

For residents living near the site, the discovery came as a shock.

Florence Banjo, a farmer from the nearby village of Abidagba, said the smell from the laboratory often drifted into the community. She believed it came from a pig farm and never suspected a drug operation hidden in the forest.

She also recalled that construction activity around the site had sparked hopes of development.

"We heard rumours that they were going to build (a housing) estate there, and I was happy that they'd finally pave the road that leads into our village," the 59-year-old told AFP.

"We were disappointed."