John Lewis
John LewisReuters

John Lewis, a US congressman and controversial civil rights activist and close confidant of former US President Barack Obama, passed away on Friday following a six-month battle with cancer.

Lewis was 80 years old at the time of his death.

The long-time civil rights activist was a strong proponent of the Blacks Lives Matter movement and wanted to see them represented in the White House.

Following news of his death, US President Donald Trump tweeted: "Saddened to hear the news of civil rights hero John Lewis passing. Melania and I send our prayers to he (sic) and his family."

In a statement quoted by CNN, Obama wrote, "I first met John when I was in law school, and I told him then that he was one of my heroes. Years later, when I was elected a U.S. Senator, I told him that I stood on his shoulders. When I was elected President of the United States, I hugged him on the inauguration stand before I was sworn in and told him I was only there because of the sacrifices he made."

Lewis "never stopped providing wisdom and encouragement" to Obama and his family, the statement added. "We will miss him dearly."