Obama's immigration reforms
US President Barack Obama pauses while speaking about immigration reform during a visit to Del Sol High School in Las Vegas, NevadaKevin Lamarque/Reuters

Central American leaders and the Mexican president have hailed US President Barack Obama's sweeping immigration reforms though he faced sharp criticism from the Republicans.

Obama's overhaul of the US immigration system protects up to five million undocumented immigrants from deportation.

"This is an act of justice which recognises the great contribution of millions of Mexicans to the development of our neighbour," Mexican president Pena Nieto told reporters shortly after Obama's announcement.

Of the 11 million estimated unauthorised immigrants in the US, more than half are thought to be Mexicans.

Nieto acknowledged the latest plan would allow scores of Mexican families to stick together.

A statement from the office of Honduran President Juan Orlando Hernandez said: "This temporary relief is a great step in the right direction from the United States to resolve the migratory issues of 11 million people, and so we urge Congress to permanently resolve their status by approving a deep immigration reform."

He added that the latest move conveys a "powerful message of solidarity with Latin America".

Central American leaders from Guatemala and El Salvador have also welcomed Obama's latest announcement.

Meanwhile, the US president continued to face criticism from the Republicans for using his executive powers.

Despite the sharp reaction, Obama has not only defended his move but also pledged to press ahead with his immigration reform agenda.

"I will never give up," he said, speaking at a public rally in Las Vegas. "We're going to keep on working with members of Congress to make permanent reform a reality."

"But until that day comes, there are actions that I have the legal authority to take that will help make our immigration system more fair and more just, and this morning I began to take some of those actions."

"When members of Congress question my authority to make our immigration system work better, I have a simple answer - pass a bill."