Nokia is apparently set to unveil new additions to its Lumia line, with speculation that announcements could come as early as this week.

The company is expected to unveil Lumia 630, another mid-tier device that is expected to run the next generation of Microsoft’s Windows Phone platform – Windows Phone 8.1, which is also expected to be detailed imminently.

It would have a 4.5-inch WVGA resolution screen, and be powered by a 1.2GHz quadcore Qualcomm processor (similar to that found in the Moto G). It will also include a 5MP camera without flash, and also dispenses with the hardware camera button – previously a requirement for Windows Phone devices.

It is also likely to feature dual-SIM support.

The device is likely to be the replacement for Lumia 625, which was announced in July 2013. At the time, the 4.7-inch screen device was the largest in the Lumia range, although it has subsequently lost this crown.

Also apparently in the works is Lumia 930, a device that has been described as the international version of the Verizon Wireless-exclusive Lumia Icon (pictured).

Icon is a high-end device with 5-inch HD screen, 2.2GHz quadcore processor, and 20 megapixel camera. It has been suggested Lumia 930 will feature a 4.5-inch screen.

There does appear to be some doubt about whether this smartphone will be launched imminently, and if so, whether it will use Windows Phone 8.1.

While Lumia Icon uses the preceding version of the platform, there is a danger that Lumia 930 will look outdated if unveiled without support for the new OS.

As much as the new device launches, speculation has also focused on changes to the Windows Phone platform.

This is expected to introduce a new notification centre, offer an improved camera interface, feature new homescreen animations, and mark the introduction of Cortana, a Siri-type voice assistant.