The US state of Texas is preparing to build a barrier on the Rio Grande River in bid to prevent irregular migrants entering from border with Mexico.

A tweet by the Texas Department of Public Safety featured pictures of large orange buoys being transported to be installed on the river in the town of Eagle Pass.

"The buoys have arrived and the installation of the marine barrier on the Rio Grande begins today," it said.

Governor Greg Abbott noted the floating barriers could be moved if necessary and extended to multiple parts of the river.

But migrant rights advocates warn that the buoys may cause deaths in river crossings, while environmentalists objected to the measure on the grounds that barriers on the water surface will affect the flow of the river and natural life.

Four irregular migrants, including a baby, drowned in the first week of July trying to cross the Rio Grande in the Eagle Pass area.

Eagle Pass is at the top of Texas border crossing points where irregular immigrants enter illegally.

Lawsuit

However, a Texas businessman has filed a lawsuit in a bid to stop the state's governor from placing the buoys in the Rio Grande River, the man's lawyer said on Saturday.

Businessman Jessie Fuentes, owner of Epi's Canoe and Kayak Team, said Abbott's plan would place a "wall" of buoys in the exact location near Eagle Pass where his firm offers river tours.

Fuentes is suing the state and Texas officials to stop the operation.

"The governor and the defendants do not have the legal authority under Texas law or federal law to install those buoys," Carlos Flores, Fuentes's lawyer, told the AFP news agency.

The lawsuit further asserts that the emplacement of the buoys would require federal approvals that, as of Friday, Abbott had yet to receive.

The buoy installation is part of a "Lone Star" operation the state is pursuing to secure its borders.

Previously, during the Covid-19 pandemic, US authorities invoked a law known as Title 42 to swiftly expel an array of migrants on public health grounds — usually without sanctions — but that authority ceased on May 11 when t he government declared an end to the health emergency.

Since then, a law known as Title 8 has prevailed, providing for strict penalties for those crossing who do not qualify for asylum, including five-year bans on entering the country and possible criminal charges.

The change has led to a "significant reduction" in the number of migrants reaching the southwest US border, federal officials said in mid-June.