Washington DC - A federal judge on Thursday temporarily blocked a Texas law that would allow state police to arrest and deport migrants who cross illegally into the United States from Mexico.

The administration of President Joe Biden had sued to halt the law known as Senate Bill 4 (SB 4), which had been scheduled to take effect next week.

US District Court Judge David Ezra issued a preliminary injunction preventing it from going into force, citing previous court rulings that "states may not exercise immigration enforcement power except as authorized by the federal government."

"SB 4 conflicts with key provisions of federal immigration law," Ezra said.

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The ruling came as Biden and Donald Trump, his likely Republican opponent in the November presidential election, were paying dueling visits to the US-Mexico border on Thursday.

Republicans blame Biden for the recent record number of migrants entering the United States, while the White House says Trump's party is deliberately sabotaging a bipartisan attempt to find a solution.

Greg Abbott, the Republican governor of Texas and a Trump ally, said he would appeal the district court judge's ruling on SB 4.

"The president of the United States has a constitutional duty to enforce federal laws protecting states, including laws already on the books that mandate the detention of illegal immigrants," Abbott said.

"Texas has the right to defend itself because of President Biden's ongoing failure to fulfill his duty to protect our state from the invasion at our southern border."

SB 4 is the latest flashpoint between the Republican governor and federal authorities.

The Justice Department has also filed a lawsuit seeking the removal of a floating barrier installed by Texas authorities in the Rio Grande river to stop migrants crossing from Mexico.