Anthropic's Claude large language model is powering the majority of complex tasks for Amazon's new Alexa+, sources tell CNBC.

Amazon on Wednesday unveiled the first major overhaul of its Alexa voice assistant since its introduction more than a decade ago, embedding it with generative artificial intelligence.

Alexa Plus will start rolling out next month in early access. It's an opt-in service and won't be available to everyone through an over-the-air update in March.