Nokia revealed two new budget Lumia smartphones at Microsoft's Build 2014 on April 2, Digital Spy reported.

The Lumia 630 and 635 will be among the first handsets to feature Microsoft's upcoming Windows Phone 8.1, Stephen Elop announced at the event.

"[The devices are] an uncompromised Microsoft experience and an uncompromised Lumia experience to more people at much lower price points", Elop said.

Two versions of the Lumia 630 are available - single-SIM 3G and 3G dual-SIM - while the Lumia 635 is a 4G model that supports one SIM only.

Both smartphones feature a Snapdragon 400 quad-core 1.2Ghz processor with a 4.5-inch, 854 x 480-resolution display and 5-megapixel, back-facing camera.

The two handsets are also 9.2mm thick and weigh 134g, with Bluetooth 4.0 support and a 1830mAh battery.

Although they share the same battery capacity, the Lumia 635 is able to provide slightly longer 3G talk time - 14 hours compared to the Lumia 630's 13.1 hours.

Memory is also the same, with 512MB of RAM and 8GB of internal storage expandable by memory card.

The Nokia Lumia 630 is expected to roll out in May in Asia, Russia, China, India and Europe from $159 for the single-SIM variant and $169 for the dual-SIM variant.

Meanwhile, the Nokia Lumia 635 will be "broadly available" in regions including the US in the summer, from $189.