Washington, Oct 9 (IANS): US President Barack Obama has said "anti-immigrant sentiment" in the US is "not new but it is wrong" and rejected the "inflammatory" speeches and positions of those who fly the "flags of intolerance".

In his speech at the Congressional Hispanic Caucus Awards Gala on Thursday, Obama, without taking names, alluded to Republican front-runner Donald Trump who caused a great row countrywide over his anti-immigrant comments, Efe news agency reported.

"Leadership is not fanning the flames of intolerance and then acting all surprised when a fire breaks out. Saying clearly inflammatory things and then saying 'well that's not what I meant', until you do it again and again and again... the anti-immigrant sentiment that has affected our politics is not new but it is wrong," said Obama.

"America's greatness does not come from building walls. It comes from building opportunity," he added.

The president also revived one of the most effective slogans during his re-election campaign, "Do not boo, vote. They can't hear the boos, they can hear your vote".

Obama also emphasised the importance of Latinos registering to be able to vote in the next election and not let their political silence translate into a victory for Republicans who are looking to restrict their rights.

However, Obama also acknowledged changes do not happen overnight nor in a single legislature or in the time served by a president and urged people including the Latino community to vote in order to continue working on those changes.

Regarding the block in Congress on immigration reform, he said it cannot continue on grounds of false arguments when figures clearly show border security to be far more effective than ever while experts agree it would be detrimental to the country's economy.

Obama also offered rare praise to predecessor George W. Bush who "made immigration reform one of his priorities" while his Republican colleagues now refuse to agree to rectify an immigration system that everyone knows to be inefficient.