The Pope has indirectly criticised some of the most contentious policies of the US government during a historic speech to Congress.

During his six-day visit to the US, Pope Francis addressed Congress and the US people on Friday morning (AEST), urging law makers to abolish the death penalty, restrict the arms trade, treat migrants more humanely and fight climate change.

He said the US “must not repeat the sins and the errors of the past” when dealing with immigrants.

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“In recent centuries, millions of people came to this land to pursue their dream of building a future in freedom.

“We must not be taken aback by their numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation … to respond in a way which is always humane, just and fraternal.”

The Pope touched on Immigration, weaponry and climate change, amongst other topics. Photo: Getty

He spoke of the plight of poor Central Americans and Mexicans who make deadly treks across the Mexican border.

Last year, efforts by both sides of government to improve immigration laws failed and the US experienced a flood of more than 60,000 unaccompanied minors from Central America rushing to the US.

Again, challenging many of the Republicans and some Democrats in the chamber, the Pope called for a worldwide end to the death penalty – the US is one of a handful of countries to still administer it.

He said the arms trade was being fueled by hunger for “money that is drenched in blood”.

A well-known critic of the damage caused to the environment, Pope Francis said Congress had a crucial role to play to “avert the most serious effects of the environmental deterioration caused by human activity”.

This was the most politically charged part of the speech, considering the majority of Republicans in Congress had challenged scientific conclusions on climate change, The Guardian reported.

He said climate change could “no longer be left to a future generation” to tackle.

At the end of the speech, Democrats leapt to their feet to applaud, while Republicans at first resisted, but then relented, The Guardian reported.

Later on Friday, the Pope was to leave for New York where he will address the United Nations on Friday.

He wraps up his six-day US trip on Saturday and Sunday in Philadelphia at an international festival of Catholic families.

– with agencies