A federal appeals court on Monday blocked measures announced by US President Barack Obama last year that give work permits and deportation protection to some four million undocumented migrants.

Obama issued decrees in November 2014 allowing people who illegally immigrated to the United States but whose children are legal residents, to remain in the country while their legal status is resolved and be allowed to work.

The measure affects more than four million people who would otherwise risk deportation.

Obama's measures however were quickly challenged by conservative governois of 26 US states, arguing that it was up to Congress, and not the president, to enact immigration reform. Afederal court in Texas in February ruled in their favor.

On Monday, in a 2-1 vote, the Fifth Circuit Appeals Court based in New Orleans ruled against an Obama administration request to overturn the February ruling.

There are nearly 12 million unauthorized immigrants living in the United States. Republicans and Democrats agree that sweeping immigration reform is long overdue, but bitterly disagree on how to do it.

The White House yesterday said it will now take their case to the US Supreme Court. But it's unclear if a ruling can be issued before Obama leaves office in January 2017.