Comcast on Wednesday said its internet speeds will jump substantially for as many as half its customers in Oregon and southwest Washington.

Speeds will more than double for many customers and quadruple for some, but only for those who also subscribe to Comcast's TV service.

Comcast isn't raising prices now - its annual rate hike usually comes in the fall. By restricting the faster speeds to cable TV customers, the company could be looking to compel those subscribers to retain that service.

A growing number of viewers are turning to streaming alternatives like Netflix, Hulu and YouTube. Comcast lost 200,000 residential video subscribers nationwide last year, according to its financial statements, despite adding more than 1 million internet customers.

Comcast says it will notify customers who are eligible for the speed increase, and most of them only need to reset their modem to get the faster connection. The company says it will notify customers who lease a modem if they need an upgrade, which it will provide at no additional cost.

Speed increases vary by plan, but some will increase from 60 megabits per second to 150 Mbps. High-end plans will go from 250 Mbps to 1 gigabit per second (a gigabit is 1,000 Mbps.) Affected plans include Performance Plus, Performance Pro and Blast Pro.

Monthly prices for the new service tiers range from $80 to $220, depending on the level of service and whether customers are eligible for introductory prices or loyalty discounts.

Here's a rundown of the faster speeds:

Internet Tier/Customer Package Current Download Speed (Mbps) New Download Speed (Mbps) Performance Plus / Saver, Double, Triple or Quadruple Play 60 150 Performance Pro / Starter, Triple Play 150 250 Blast! Pro / Preferred and Premier, Triple Play 250 400 Blast! Pro / Preferred and Premier, Quadruple Play 250 1 Gig

-- Mike Rogoway; twitter: @rogoway; 503-294-7699