Colin Powell, the first Black US secretary of state and top military officer, has died at the age of 84 due to complications from Covid-19.

"We have lost a remarkable and loving husband, father,grandfather and a great American," his family said, thanking the staff of the Walter Reed National Military Medical Center near Washington who treated Mr Powell, but providing few details about his illness.

His family said that Powell was fully vaccinated against Covid-19.

Powell was one of America's most prominent Black figures for decades. He served three Republican presidents in senior posts and reached the top of the US military as it was regaining its vigour after the trauma of the Vietnam War.

He was the top US general when US-led forces drove Iraqi troops from Kuwait in 1991 and the chief US diplomat when the United States relied on erroneous intelligence about Iraqi weapons of mass destruction to justify its 2003 invasion of Iraq.

Secretary of State Colin Powell pictured in 2003 with US President George Bush

In a brief statement, the Powell family said he had died this morning from Covid-19, had been fully vaccinated against the disease, and thanked the medical staff who cared for him.

The statement did not address such matters as what vaccine he received or whether he had gotten a booster shot, when he fell ill, when he may have been hospitalised and whether he may have had underlying health conditions that contributed to his illness.

US news organisations reported that Powell had multiple myeloma, a cancer of plasma cells that reduces the body's ability to fight infection. Reuters could not immediately confirm the reports.

Condolences poured in from Democrats as well as Powell's fellow Republicans, including former President George W Bush.

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"Many presidents relied on General Powell's counsel and experience," Mr Bush wrote in a statement.

"He was such a favourite of presidents that he earned the Presidential Medal of Freedom - twice."

US President Joe Biden hailed former Powell for embodying "the highest ideals of both warrior and diplomat".

"Having fought in wars, he understood better than anyone that military might alone was not enough to maintain our peace and prosperity," Mr Biden said.

Colin Powell was US secretary of state-designate when pictured with Joe Biden in 2000

"Today, the nation lost a man of undaunted courage and a champion of character," added centrist Republican Senator Mitt Romney.

Former US Secretary of State Condoleezza Rice said: "Today our nation mourns the passing of a truly great man. Colin Powell spent the entirety of his life in service to his country. He was a trusted colleague and dear friend through some very difficult times."

Former British Prime Minister Tony Blair recalled Powell's self-deprecating humour, his kindness to his staff and his "willingness to work across partisan division in the interests of his country".

"Colin was a towering figure in American military and political leadership over many years, someone of immense capability and integrity, a hugely likeable and warm personality," Mr Blair said.

John Major, also a former UK Prime Minister, said Powell was "one of the finest men I ever met. And, perhaps, one of the finest Americans never to be president".

Powell served as US national security adviser under President Ronald Reagan from 1987 to 1989.

As a four-star Army general, he was chairman of the Joint Chiefs of Staff under President George HW Bush during the 1991 Gulf War in which US-led forces expelled Iraqi troops from neighboring Kuwait.

In 2008, he broke with his party to endorse Democrat Barack Obama, the first Black person elected to the White House.

Illustrating his deep misgivings about the evolution of the Republican Party as it moved to the right in recent years, Powell endorsed Democrats Hillary Clinton in the 2016 presidential election and Joe Biden last year against Donald Trump.

Powell called Mr Trump a liar who presented a danger to the United States.