One of the bodies was found tangled in a series of giant buoys installed as a barrier, raising human rights concerns.
Mexican authorities announced on Thursday that they had discovered the bodies of two people in the Rio Grande, one of them stuck in a group of buoys installed by Texas Governor Greg Abbott to stop people from crossing into the US.
“We are concerned about the impact on migrants’ human rights and personal security that these state policies could have, as they go in the opposite direction to close collaboration,” Mexico’s foreign ministry said in a statement.
The Texas Department of Public Safety (DPS) responded on Thursday that the body found tangled in the buoys appeared to have drowned earlier and floated downstream.
The second body, which remains unidentified, was discovered about 5 kilometres (3 miles) away from the first.
The buoys, criticised by rights groups as a cruel political stunt, are the subject of a lawsuit from the administration of US President Joe Biden.
In its legal filings, the US Justice Department has said that the floating buoys raise humanitarian and territorial concerns.
The Mexican government has also voiced discontent over the buoys. It has sent the US two diplomatic letters alleging that the aquatic barriers may violate Mexican sovereignty.
Governor Abbott previously rejected a federal appeal in July to remove the barrier, after Biden’s government accused the Texas governor of installing the buoys without permission.
The standoff echoes a similar situation that unfolded in Arizona last year, with then-Republican Governor Doug Ducey. He came under fire for erecting a makeshift barrier with shipping containers along the border with Mexico.
It too prompted a federal lawsuit, with the Biden administration alleging that the shipping containers damaged federal lands and threatened public safety.
But Republicans have defended the unorthodox measures, arguing that the Biden administration has been too lax in its effort to deter irregular border crossings.
While the Biden administration has criticised the buoy barrier on humanitarian grounds, critics accuse his government of continuing a decades-long policy of “prevention through deterrence”.
They argue that the government has a history of funnelling migrants and asylum seekers into perilous terrain, by narrowing the legal pathways to entry.
Migrant rights groups say that such efforts do not stop people from making the trip north but rather result in unnecessary deaths as migrants swim across rivers and cross remote stretches of desert to avoid detection.
For years, the Rio Grande has evoked fear in migrants, known for its churning waters and frequent drownings. In September 2022, nine bodies were discovered at just one point of the river in a single day.
Efforts by Abbott to escalate border enforcement at the state level have been the subject of persistent controversy. Last month, a Texas state trooper spurred an outcry after he wrote a letter describing “inhumane” border policies, including orders to push migrants at risk of drowning back into the river.