US President-elect Donald Trump has announced that Japanese tech conglomerate SoftBank Group will invest $100 billion to boost the economy and create at least 100,000 jobs.

Trump made the announcement at a news conference at his Mar-a-Lago estate on Monday. He was joined by SoftBank CEO Son Masayoshi.

Trump said, "This historic investment is a monumental demonstration of confidence in America's future, and it will help ensure that artificial intelligence, emerging technologies and other industries of tomorrow are built, created and grown right here in the USA."

The $100 billion figure is double the amount SoftBank pledged to invest during Trump's first term.

Son said: "President Trump is a double-down president. I'm going to have to double down $100 billion and 100,000 jobs. This is, you know, my confidence level." He added that his trust in the US economy has "tremendously increased" since the election.

Son spoke exclusively with NHK after holding his joint news conference with Trump.

He said the two had breakfast on Sunday morning and spent about seven hours together until late afternoon.

Son expressed confidence about the viability of the 100-billion-dollar investment, saying the SoftBank Group has hundreds of billions of dollars in assets plus various means to procure funds.

Son said: "We will carry out various AI-related investments, including data centers for AI. We already have many group firms, but will likely add more or strengthen existing ones."

He added that since the generative AI sector is rapidly growing, he is optimistic that Trump's positive efforts to promote artificial intelligence will become even more active.

The SoftBank Group CEO also stressed the significance of announcing the investment plan proactively.

He said: "Trump is likely to receive many other proposals from various firms. By acting first with speed, we can broaden our reach into various businesses and partnerships. It's better to make decisions quickly."