Chinese artificial intelligence (AI) start-up DeepSeek has been threatened with "aggressive counter-measures" amid claims it "sucked knowledge" out of US rival OpenAI for its chatbot, writes Callum Muirhead.

DeepSeek routed global tech stocks this week when it said it had developed an AI chatbot model for a fraction of the cost of its Silicon Valley rivals that was just as effective.

But OpenAI, the maker of ChatGPT, claimed DeepSeek used its tech without permission.

It came as David Sacks, Donald Trump's AI and cryptocurrency adviser, said it was "possible" that the US firm's intellectual property had been stolen.

Warning that the Chinese may have "sucked knowledge" out of ChatGPT, he added: "I don't think OpenAI is very happy about this."

San Francisco-based OpenAI said it had uncovered evidence of "distillation", a technique computer developers use to boost the performance of smaller AI models by extracting data from larger and more capable ones.

While the technique is common, OpenAI was concerned DeepSeek was using it to build a rival. This is banned under the terms of service, which state users cannot "copy" the tech or use it to "develop models that compete with OpenAI".

"We are aware of and reviewing indications DeepSeek may have inappropriately distilled," OpenAI said.

"We take aggressive, proactive countermeasures to protect our technology and will continue working closely with the US government to protect the most capable models being built here."