Image copyright Reuters Image caption John Conyers greets Barack Obama in Detroit in January 2016

The longest-serving black member of the US Congress, John Conyers, has died at home at the age of 90, police in Detroit say.

The Democrat resigned under a cloud of sexual harassment allegations in December 2017 after a career lasting nearly 53 years.

In office, he was known for his liberal stance on civil rights and liberties.

He memorably fought for 15 years to make the birthday of Martin Luther King what it is today - a national holiday.

Conyers was also a founding member of the Congressional Black Caucus.

How did his career pan out?

Born on 16 May 1929, he grew up in Detroit and served in the military for nearly a decade, including 12 months in Korea during the war there (1950-53) when he was a Combat Engineers officer.

"I like to think that my worldview was broadened by my military experience," he later reflected, according to USA Today.

Going on to train as a lawyer, he became involved in the civil rights movement.

In 1964, he narrowly won his first election in Michigan, becoming one of just six black members of the House of Representatives.

He began his campaign to create "MLK Day" (a movable holiday which next falls on 20 January) just days after the civil rights champion was assassinated in 1968.

Media playback is unsupported on your device Media caption The moment Americans learned of MLK's death

It was finally signed into law by President Ronald Reagan in 1983.

He was involved in reforms ranging from the Violence Against Women Act of 1994 and the Hate Crimes Act of 2009 to the Jazz Preservation Act of 1987, the Detroit News recalls.

He was also the only House Judiciary Committee member to have sat in on two presidential impeachment hearings: for Richard Nixon in 1974 over Watergate, and for Bill Clinton in 1998 over his relationship with a female intern.

He died on Sunday, apparently of natural causes, the Associated Press reports.

What were the allegations made against him?

In November 2017, he admitted to settling a wrongful dismissal complaint in 2015 with a former employee who had accused him of sexually harassing her - but he denied misconduct.

Image copyright Reuters Image caption On Capitol Hill in July 2008

More women came forward to accuse him of sexual misconduct, but he continued to deny wrongdoing:

Elisa Grubbs, who had worked for Conyers from about 2001 to 2013, accused him in a sworn legal statement of having slid his hand up her skirt as the two sat in church together

His former deputy chief of staff, Deanna Maher, came forward to say she had rejected him when he had asked her to his hotel room to have sex in 1997, and that he had subsequently groped her several times

Top Democrat Nancy Pelosi and her then Republican counterpart, House Speaker Paul Ryan, both called on Conyers to step aside.

"I vehemently deny any and all allegations of harassment or dishonor," Conyers was to say later, "but I recognize that in this present environment, due process will not be afforded to me. I was taught by a great woman, my mother, to honor women."

Notwithstanding the shadow cast over his career by the misconduct allegations, fellow Democrats paid tribute to Conyers.

"His impact on our state, whether by spearheading reforms in criminal justice and voting rights in Congress or through his lifetime of civil rights activism, will not be forgotten," Michigan Governor Gretchen Whitmer said in a statement.

Democratic presidential hopeful Bernie Sanders tweeted to "celebrate" the late congressman's "extraordinary service".