Microchip maker Nvidia said it would be hit with $5.5bn (£4.2bn) in costs after the US government tightened export rules to China.

The chip manufacturing giant, which has been at the heart of the artificial intelligence (AI) boom, will require licences to export its H20 AI chip to China, which has been one of its most popular.

The rules come amid an escalating trade war between the US and China, with both countries introducing steep trade tariffs on each other covering various goods.

Nvidia shares plunged almost 6% in after-hours trading.