The Z10 is controlled via a 4.2in (10.7cm) touchscreen while the Q10 has a smaller 3.1in (7.9cm) screen and physical keyboard.

The UK will be the first to get the Z10 where it will launch on Thursday.

Its appeal could determine whether the firm – which has switched its name from Research In Motion to Blackberry – has a long term future.

The new operating system had originally been due for release last year. Canada and the UAE will get the Z10 in February and the firm said it should go on sale in the US in March.

“Two years ago we had to make a very serious decision,” chief executive Thorsten Heins told a press conference in New York.

Blackberry said users had wanted a phone with a physical keyboard

“Adopt someone else’s platform or build a whole new one from ground up for Blackberry. And we made the tough call to go it alone.

“Bringing an entirely new platform to the market and ushering this company through a really difficult transition took careful planning and we absolutely knew it was risky.”

Shrinking share

According to data from IDC, Blackberry devices used to account for just over 19% of global smartphone shipments at the start of 2010 – but it suggests that figure had dropped to less than 4% by the end of last year.

“The devices are probably the firm’s last attempt to make in impact in this market,” Alexander Peterc, technology analyst at BNP Paribas, told the BBC.

“The firm’s market share has fallen because they haven’t had a product launch in a year and a half. BB7 – the previous system upgrade which was just incremental – was, let’s say, a failure.

“They still have a following in enterprise where they will probably find a reliable source of revenue for the next 12 months but it’s also crucial for them to generate at least a half-decent amount of traction with consumers.”

Touchscreen keyboard

The new user interface allows up to eight apps to run simultaneously, four of which can appear in small windows on the same screen – something the firm describes as “true multitasking”.

Michelle Fleury spoke to chief executive Thorsten Heins, and looked at the Blackberry 10’s ‘hub’ feature

During a demonstration executives said the intention was to let users “flow” through applications using swipes and other gestures rather than copy the “in and out” nature experienced when navigating rivals’ devices.

For example BB10’s Hub – which brings together emails, texts and other notifications – can be accessed by swiping up and then to the right from any app. The user then needs to reverse the gesture to return to where they were.

The BBM messaging app can now make audio and video calls as well as being able to share what is on one person’s screen with the other user’s device.

The Z10 is not RIM’s first to feature a touchscreen keyboard, but it has adopted new features to attract users more used to physical buttons.

These include a feature which learns the words and phrases the owner most often types and then uses this to suggest words which float above the keyboard and can be flicked into place.

It will also learn to anticipate and correct frequently made mistakes – such as if the user often hits the letter C when they mean to tap space.

Blackberry head of software Vivek Bhardwaj demonstrates the new BBM video feature

“The new keyboard is the jewel in the crown and Blackberry has mastered the experience,” said Francisco Jeronimo, European mobile devices research manager at IDC.

“The browser, one of the weakest features on the old Blackberry devices, is now an enjoyable experience.

“This is not a new Blackberry device, this is a completely new Blackberry experience. For the first time the traditional keyboard Blackberry users will it find easier to type on a touchscreen.”

The handsets also include a mix of features designed to make them appeal as a crossover business-personal machine.

Blackberry Balance sets up a “work perimeter” on the phones so that data belonging to the user’s employer can be limited to approved apps, while photos and other personal information can be used across a wider range of software.

Companies are also given the option of being able to remotely wipe sensitive files.

Meanwhile the in-built Pictures app includes a facility called Timeshift designed to ensure everyone has their eyes open in group photos.

It involves the user taking several pictures in a row and then scrolling through the shots to select the best frame.

Tough competition

Blackberry said it had secured more than 70,000 additional apps for its Blackberry World app store including Skype, Angry Birds, Facebook and Whatsapp.

In addition it offers music, TV shows and movies. However, there is no official YouTube app.

A demonstration of the Timeshift feature did not result in a totally successful shot

But some analysts suggested its efforts might have come too late to make much headway against the most popular smartphone platforms: Google’s Android and Apple’s iOS.

“Blackberry continues to face the twin demons of consumer-driven buying power and a chronic inability to appeal to mature market consumers,” said Jan Dawson, chief telecoms analyst at Ovum.

“There is nothing in what we’ve seen so far of BB10 that suggests it will conquer the second of these demons, and the first is utterly out of Blackberry’s control.

“We don’t expect a speedy exit from the market; with no debt, 80 million subscribers and profitability in the black in at least some recent quarters, the company can continue in this vein for years. But its glory days are past, and it is only a matter of time before it reaches a natural end.”

Blackberry’s shares fell more than 6% following the launch.