Samsung Electronics has rolled out the voice command feature on its Bixby virtual assistant for the Galaxy S8 and S8 Plus in South Korea, which was missing when the phones were launched last month.

Samsung began the voice command service at 1pm KST on Monday, after sending a notice in the morning to users of the smartphones.

Bixby, the company's artificial intelligence (AI) assistant, rolled out on April 21 when official sales of the S8 series began in South Korea.

It supported vision, reminder, and home features, but the voice command feature was absent. Samsung previously said it wanted to fully prepare before rolling out voice.

Voice command is yet to reach other markets where the S8 is available. US customers are yet to get the feature, but it will likely deployed in May.

The Galaxy S8 and S8 Plus have shown robust sales since launching. It hit over 1 million pre-orders in South Korea and Samsung said it saw double digit growth compared to the S7.

However, there have been some hiccups along the way. Some customers in the US have complained of the phones randomly rebooting.

The company also rolled out a software update following user complaints of the phones having a red-tinted display, but stressed that there was no quality issue.