Anthropic is close to closing a funding round of around $20 billion (£14bn) that would value the start-up at around $350bn, making it one of the world’s most valuable private companies, on the back of strong investor demand to contribute, according to multiple reports.

Anthropic received initial commitments of $10bn to $15bn on Tuesday, a figure that is expected to rise as it completes the round in the coming weeks, the Financial Times reported, with similar information appearing in subsequent reports from other news outlets.

The start-up had reportedly been in talks for about $10bn in funding from investors, but the amount has since doubled due to strong demand.

Anthropic received demand that was five or six times its original target, one source told the FT, with investors keen to sink funds into a firm that is seen as one of OpenAI’s chief competitors, alongside Google and others.

Singapore’s sovereign wealth fund GIC and US investor Coatue are leading the deal, with a large contribution from Sequoia Capital and expected participation from existing investors Iconiq Capital, Altimeter Capital, Lightspeed Venture Partners, Menlo Ventures, G Squared and Factorial Funds.

In addition to the expected $20bn from investment groups, Microsoft and Nvidia announced plans in November to invest up to $5bn and up to $10bn, respectively, into Anthropic.

It was not clear whether the two tech giants would participate in the current round and, if so, how much they would contribute, CNBC reported, citing unnamed people.