A U.S. court has backed a temporary hold on President Barack Obama's plans to shield almost five million illegal immigrants from deportation, BBC News reports.

The hold was imposed after 26 states launched a legal challenge against the executive action, alleging it was unconstitutional.

An appeals court has now denied a government request to overturn it.

The White House said the action was essential to fix a "broken immigration system".

Under the plans, announced last year, people who entered the U.S. illegally as children and parents of children who are U.S. citizens would be offered temporary protection from deportation.

Aside from arguing President Obama acted outside his authority, the states say the move forces them to invest more in law enforcement, health care and education.

The 5th U.S. Circuit Court of Appeals' ruling keeps the plans on hold while the states' legal challenge proceeds. It is not clear yet whether the Obama administration will appeal.

The White House said the president acted within his powers to fix a "broken immigration system".

The Justice Department has argued that immigration policy is for the federal government to determine, not the states. The department is now evaluating its next steps, a U.S. official told Reuters on the condition of anonymity.

The Republican governor of Texas, Greg Abbott, who has been a persistent critic of the president's immigration policies, tweeted: "The constitution wins".