Outgoing US President Joe Biden warned of the dangers of an oligarchy gaining power as he delivered his farewell address and brought a decades-long career in politics to an end.

?Today, an oligarchy is taking shape in America of extreme wealth, power and influence that really threatens our entire democracy, our basic rights and freedom,? he said on Wednesday.

Biden, 82, took aim at an ultra-wealthy ?tech-industrial complex? which he said could wield unchecked power over Americans.

He also used his final televised speech from the White House to issue warnings about climate change and social media disinformation.

Speaking from the Oval Office where his family had gathered to watch, he touted his single-term administration?s record, referencing job creation, infrastructure spending, healthcare, leading the country out of the pandemic, and making the US a safer country.

He added, however, that ?it will take time to feel the full impact of all we?ve done together, but the seeds are planted, and they?ll grow and they?ll bloom for decades to come?.

Biden wished Donald Trump?s incoming administration success, but then issued a series of pointed warnings, with the president stating "so much is at stake right now?.

On climate change, he said ?powerful forces want to wield their unchecked influence to eliminate the steps we?ve taken to tackle the climate crisis to serve their own interests for power and profit?.

On misinformation, Biden warned that ?Americans are being buried under an avalanche of misinformation and disinformation, enabling the abuse of power?.

He also took a swipe at social media companies such as Meta, which has recently announced it will get rid of independent fact checkers. ?Social media is giving up on fact checking. The truth is smothered by lies told for power and for profit,? Biden said.

And his attack on an ultra-wealthy ?tech-industrial complex? was a veiled reference at Silicon Valley executives such as Elon Musk, the world?s richest man who is close to Trump and provided huge financial backing to his campaign.

His language echoed that of President Dwight Eisenhower who famously warned of a ?military industrial complex? in his 1961 farewell address.

Biden appeared to have Musk in mind when he warned of a ?dangerous concentration of power in the hands of a few ultra-wealthy people?.

The term oligarchy refers to a government that is run by a handful of people, often for their own gain.

The president went on to say there could be ?dangerous consequences if their abuse of power is left unchecked?.

Other tech bosses such as Jeff Bezos and Mark Zuckerberg have also made efforts to improve relations with Trump ahead of his return to the White House.

Closing his exit speech, which is a longstanding presidential tradition, Biden called on Americans to ?stand guard? of their country: ?May you all be the keeper of the flame.?

His farewell address came on the same day he announced a ceasefire agreement between Israel and Hamas, which he referenced in his opening remarks.

Biden said the negotiations had been some of the toughest of his career, and took credit for helping get the deal over the line.

The deal will see a ceasefire take effect on 19 January, a day before Trump is due to take office. The incoming president has also taken credit for the agreement, saying it was only possible because he won the election in November.

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