Federal leaders are paying tribute to the sacrifices of Indigenous veterans as well as the discrimination they faced after returning from war.

Prime Minister Justin Trudeau says all flags on federal government buildings, including the Peace Tower on Parliament Hill, were lowered to acknowledge the service of Indigenous veterans.

He told his Caucus this morning that Indigenous people who served across this country often faced systems and discrimination and barriers that were greater than they were for others.

It is estimated that more than 12,000 Indigenous people joined the Canadian military during the First and Second World Wars and Korea.

More than 500 were killed and countless more injured.

Many of those who returned to Canada ended up falling through the cracks after they were denied the same benefits provided to non-Indigenous veterans, while others found out they had lost their Indian status by putting on a uniform.

While not formally recognized by the federal government, Indigenous Veterans Day has been growing in size and scope each year on November 8th.

Conservative Leader Erin O'Toole marked the occasion by narrating a video about Tommy Prince, who became one of Canada's most decorated Indigenous soldiers while fighting in the Second World War and Korea but who eventually became homeless before dying in 1977.

NDP Leader Jagmeet Singh led his caucus in honouring the sacrifices of Indigenous veterans at the National Aboriginal Veterans Monument in downtown Ottawa.

He described the treatment of those Indigenous veterans as an injustice, as he paid homage to those currently serving in uniform.

There are more than 2,500 Indigenous people currently serving in the Canadian Armed Forces.