Republican nominee Donald Trump delivered a lengthy, racially-charged speech on immigration where he reiterated his desire to build a wall on the US-Mexico border and outlined a policy of mass deportations of undocumented immigrants.

Only hours earlier, he met Mexican President Enrique Peña Nieto where he spoke of the "great contributions of Mexican-American citizens".

But in the speech in Phoenix, Arizona, Trump said: "We agree on the importance of ending the illegal flow of drugs, cash, guns, and people across our border, and to put the cartels out of business".

He quickly delved in to his proposals to fix the US immigration system, which he said were "worse than anybody ever realised." The presidential nominee claimed the current immigration system fails to serve the American people.

"When politicians talk about immigration reform, they usually mean the following: amnesty, open borders, lower wages," Trump said. "Immigration reform should mean something else entirely. It should mean improvements to our laws and policies to make life better for American citizens."

Trump added that not all immigrants will be able to "successfully assimilate," arguing that sometimes it simply does not work out. "It's our right, as a sovereign nation to choose immigrants that we think are the likeliest to thrive and flourish and love us."

The GOP nominee argued that undocumented immigrants have killed "countless innocent American lives" and railed against "sanctuary cities" and policies of the Obama administration and Democratic rival Hillary Clinton.

"While there are many illegal immigrants in our country who are good people, many, many, this doesn't change the fact that most illegal immigrants are lower skilled workers with less education, who compete directly against vulnerable American workers, and that these illegal workers draw much more out from the system than they can ever possibly pay back," he said, according to a transcript from the Washington Post.

Donald Trump
Republican presidential nominee Donald Trump pulled no punches at the campaign rally in Phoenix, Arizona, US, 31 August REUTERS/Carlo Allegri

Trump countered Clinton's immigration policies with a 10-point plan, whose key policy would be a wall which "Mexico will pay for," he said despite Peña Nieto's repeated assurances that Mexico would not.

"They don't know it yet, but they're going to pay for it," he said, describing a wall that will include ground sensors, towers, aerial surveillance and additional manpower.

Trump also said he would end catch and release. "Under my administration, anyone who illegally crosses the border will be detained until they are removed out of our country and back to the country from which they came," he said.

He said there would be "zero tolerance for criminal aliens", and that the estimated two million criminal undocumented immigrants would be removed in a joint operation between local, state and federal law enforcement.

Donald Trump in Mexico
Before his keynote immigration speech, earlier in the day Donald Trump (R) delivered a joint press conference with Mexican President Enrique Pena Nieto in Mexico City YURI CORTEZ/AFP/Getty Images

"Day one, my first hour in office, those people are gone. And you can call it deported if you want. The press doesn't like that term. you can call it whatever the hell you want. They're gone."

Undocumented

Trump added that his administration would issue detainers for undocumented immigrants arrested for any crime and would begin the deportation process immediately. He vowed to triple the number of ICE deportation officers and said his administration would hire 5,000 more Border Patrol agents. It should be noted that the bipartisan Gang of Eight bill, which failed to pass, called for 20,000 new agents.

Trump also said he would block funding for so-called sanctuary cities and end Obama's executive orders on immigration.

For refugees coming in from Syria and Libya, Trump proposed creating safe zones funded by Gulf nations in the war-torn countries. He called for screenings and an ideological certification "to make sure that those we are admitting to our country share our values and love our people." Applicants would be asked about their views on radical Islam, women, gays and minorities.

Trump said his administration will force countries to take back immigrants who are deported and vowed to complete the biometric entry-exit visa tracking system. He said his administration would fight against immigrants overstaying their visas.