US President Barack Obama has delivered his final State of the Union address to a joint session of Congress in Washington.

He outlined his accomplishments over the past seven years and urged Americans to overcome their fears and work together to "fix" the nation's politics.

He said doing so would help America deal with the challenges it faces, and that a rising standard of living and a peaceful planet are within reach.

Keeping with tradition, Mr Obama spoke about his vision for the United States beyond his last year in office - and what he would like to see Congress work on.

Mr Obama said he would launch a new national effort to cure cancer, with Vice President Joe Biden leading the mission.

He described militants of the so-called Islamic State group as "killers and fanatics who have to be rooted out, hunted down and destroyed" and urged Congress to approve the use of military force for the fight against the group. 

Mr Obama accused critics of playing into the hands of the so-called Islamic State group by comparing the fight against the militant group to world war three.

Mr Obama expressed regret at the highly partisan tone of debate in Washington and admitted he had failed to bridge the political divide, saying "It's one of the few regrets of my presidency, that the rancour and suspicion between the parties has gotten worse instead of better".

Mr Obama's final address came as campaign rhetoric for November's presidential election intensifies - with candidates fighting over illegal immigrants, wage inequality and violence.

The Republican response to Mr Obama's address was delivered by South Carolina Governor Nikki Haley.

She took a softer tone on immigration than the harsh line often heard from her party's presidential candidates.

The 43-year-old daughter of Indian immigrants noted that "immigrants have been coming to our shores for generations to live the dream that is America."

She added that "during anxious times, it can be tempting to follow the siren call of the angriest voices. We must resist that temptation. No one who is willing to work hard, abide by our laws, and love our traditions should ever feel unwelcome in this country."