Passengers on the boats, including British tourists, are being held by a community group in the Peruvian Amazon, local media said.
The group, believed to be from an indigenous community, said they had been arrested in protest of the government’s lack of action to deal with oil spills in a river, according to RPP Noticias.
Seventy passengers, including people from the United Kingdom, the United States, Spain, France and Switzerland, were being held after traveling on riverboats, he said.
Among them is a one-month-old baby, people with disabilities and pregnant women.
One of the foreigners would have raised the alarm on social networks.
“The faster they are heard, the faster they will let us go. Help me share, we are physically fine. Help me help them be heard,” he wrote on Facebook.
The protesters, from the Urarinas district in northern Loreto province, say two children and a woman have died in the area due to oil spills from a 40-year-old pipeline in the Cuninico River.
Community members have told local media that they plan to detain the tourists for about six to eight days.
Officials have moved to the area to deal with the dispute.
The pipeline, which carries crude oil from the Amazon region to the northwestern city of Piura, has been the site of several oil spills in recent years.
Communities in the area had already blocked boats in the river in protest.
The latest oil spill of about 2,500 barrels into the Cuninico River is reported to have occurred on September 16.
The 500-mile pipeline is owned by Petroperú, a state oil company, which said at the time that the spill was the result of “intentional” damage.