Sarah Tew/CNET

Amazon's Fire TV may be moving into the lead among video streaming devices, with its lineup of products attracting "well over" 30 million active users, the company said Wednesday at CES.

That's up from the 25 million Amazon disclosed in October, suggesting growth of 5 million new accounts in three months. And Amazon expects the number to grow soon, too.

"We're still in the middle of the 'buy' to 'turn on' period" from the holiday shopping season, Amazon's head of Fire TV, Marc Whitten, said in an interview with CNET on Wednesday at CES.

The 30 million figure seems to put Fire TV ahead of Roku, widely considered one of the most popular streaming-video products. Earlier this week, Roku estimated it had 27 million active users. The company said it defines an active account as one that has streamed content in the last 30 days; a single account may include streaming on multiple devices with multiple individuals in the household. Roku declined to comment on Amazon's announcement.

Amazon didn't characterize its definition of a monthly active user. The company has Fire devices that work in more than 80 countries, according to its support page. Roku operates in 23 countries.

The market for video streaming devices is exploding. The number of households with a streaming player has quadrupled in the last five years, according to Parks Associates, and Roku and Amazon have been competing for market share since Amazon launched the Fire TV line in 2014.

Whitten plans to grow the Fire TV business this year by expanding Amazon's international partnerships, though he avoided offering any specifics about those efforts. Whitten added that the company has been "very happy" with sales of Fire TV Edition smart TVs, which are sets that have Fire TV built into them.

As an example of a recent partnership, Amazon signed a deal last April with Best Buy to bring a new lineup of Fire TV Edition sets to customers in the US and Canada.

"Smart TV powered by Fire TV Edition, we think, is a great experience, and we want to build more of them," Whitten said.

Whitten said there's still plenty more work to do to get the right balance on promoting Amazon's Prime Video shows up against rival content on Fire TV, as well as figuring out the best experiences for controlling your TV via voice using the Alexa digital assistant. Those efforts will be works in progress over the year.

"There are things where voice is not going to be as fast [as using a remote], and there are things with voice where it's not even going to be in the same ballpark," he said, "and we're just going to keep working on making those parts great."

First published Jan. 9, 12:36 p.m. PT.

Updates, 4:20 p.m.: Adds context and more comments from Whitten interview; Jan. 10 at 9:02 a.m.: Adds context.

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