WASHINGTON, Oct 16: America’s first African-American president used the memorial of a civil rights icon on Sunday to promise better days to his financially strained nation as thousands protested against economic disparity across the United States.

Tens of thousands gathered to honour Dr Martin Luther King’s memory and pledged to carry forward his legacy. Other icons of the civil rights movement shared their history with the crowd.

Hundreds of people were arrested in Chicago and other American cities this weekend as the ‘Occupy Wall Street’ movement gained strength.

Protests were held in New York, Washington, Boston, Philadelphia and San Francisco, urging the Obama administration to reconsider its financial priorities.

At the memorial, Dr King’s 84-year-old sister, Christine King Farris, told the crowd she was happy that her slain brother “takes his symbolic place on the National Mall near America’s greatest presidents” but also urged them to “mark this wonderful day as another step towards the fulfilment of his dream”.

Earlier, Dr King’s son, Martin Luther King III, told the crowd that after bailing out banks and Wall Street, it was time to bail out working Americans.

President Obama and his predecessor at the White House have spent hundreds of billions of dollars to bail out troubled banks but did not succeed in ending the economic crisis that grips America.

Mr King said he knew where his father would be today. “I believe that if my father was alive, he would be right here with all of us — involved in this demonstration.”

President Obama’s senior political adviser David Axelrod told ABC’s “This Week” that the American people “want a financial system that works on the level. They want to get a fair share.”

Dr Martin Luther King has proved that “change can come if you don’t give up,” said Mr Obama while inaugurating the memorial at chilly but sunny Sunday afternoon in Washington.

“As tough as times may be, I know we will overcome,” Mr Obama said. “I know there are better times ahead. I know this because of the man towering over us.”

He visited the memorial with his family on Friday night. Then on Sunday morning, he walked slowly around its perimeter, alternately holding hands with daughters Malia and Sasha as memorial officials conducted a brief tour.

Mr Obama was just six years old when Dr King was assassinated in 1968, but he has said the civil rights leader blazed a path for him to follow.

Referring to Dr King’s famous “I Have A Dream” speech nearly 50 years ago, Mr Obama said: “In this place he will stand for all time among monuments to those who founded this nation and those who defended it.”

Without Mr King’s words, “we might not have had the courage to come as far as we have”, he added.

Aware of the rapidly spreading protests against disparity, Mr Obama conceded, “Nearly 50 years after the March on Washington, our work, Dr King’s work, is not yet complete. We gather here at a moment of great challenge and great change.”

He noted that a decade of rising inequality and stagnant wages had left rising poverty and millions out of work.

He urged protesters to continue to struggle for their rights.” Let us keep striving. Let us keep struggling. Let us keep climbing towards that promised land,” he said.

Hours before Mr Obama inaugurated the monument in Washington, the slain leader’s son and hundreds of his supporters gathered at the site to back the anti-Wall Street campaign.

Activist Rev. Al Sharpton, whose National Action Network organised the march, criticised US lawmakers for not passing President Obama’s jobs bill.

“If you won’t get the jobs bill done in the suite, then we will get the jobs bill done in the streets,” Mr Sharpton said to the crowd.

Although, the national unemployment rate is 9.1 per cent, it is much higher for African-Americans, 16 per cent.

Speakers at the rally said they supported Mr Obama’s bill and his re-election.

“The richest 1 per cent of Americans controls 40 per cent of this country’s wealth. Our work, brothers and sisters, is not done,” said another speaker.