Sky had already confirmed that it would be launching Sky Go Extra, a new update to its Sky Go app, this week, and now it has gone - and done it, adding new features and support for a couple of new Android devices at the same time.

The new service, which will cost £5 a month for Sky subscribers (after the first two months), will allow up to four device access the Sky Go service, rather than two previously, and more importantly will allow them to download movies and TV shows to their device to watch on the Tube or an aircraft.

Sky is hoping the offer will help it in the battle between Lovefilm and Netflix, neither of which offers downloads for offline viewing.  Unlike Lovefilm or Netflix, Sky's approach will be to offer a rolling catalogue of movies and TV shows to watch rather than go for a large permanent catalogue offering.

"All titles are available exclusively to Sky Movies subscribers and will not be available on any other online movies subscription service for a least a year after they first appear on Sky Movies," says Sky, in promoting the new service.

Sky Go Extra customers will also be able to download the latest shows from channels including Sky Atlantic, Sky 1, Sky Living and Sky Arts, as well as partner channels such as Nickelodeon and Disney.

Customers with a 64GB iPad will be able to store in excess of 400 half-hour shows and more than 80 movies. 

To sign up to Sky Go Extra, all customers need to do is visit sky.com/shop/offers/sky-go-extra.

Once they’ve done this, the next time they enter the Sky Go app they will be able to download programmes and register two more devices.

To provide even more flexibility, Sky Go customers can cancel the service at any time, subject to giving 31 days’ notice.

Sky Go customers will also be able to sign up for a two-month free trial of Sky Go Extra until the end of March.

Additionally Sky has added two new more Android devices to the list of smartphones and tablets that it supports. Users of the Motorola Razr I and the Galaxy Tab2  7.0 will now also be able to get the service.

The full list is now as follows:

Smartphones

- Google Galaxy Nexus and Nexus 4

- HTC Desire, Desire S, Desire X, Desire HD, Incredible S, Sensation, Sensation XE, One X, One XL, One S, One V and One X+

- LG 4X HD

- Samsung Galaxy S, Galaxy S II, Galaxy S III, Galaxy S III LTE, Galaxy Ace 2, Galaxy Note, Galaxy Note 2 and Galaxy Note 2 LTE

- Sony Xperia S and Xperia T

- Motorola RAZR i

Tablets

- Google Nexus 7

- Samsung Galaxy Tab 2 7.0