Asustek Computer has reportedly raised its internal shipment forecast for its ZenFone-series smartphones for 2015 from 25 million units originally to 30 million, according to sources from the upstream supply chain.

Shipments of Asustek's new ZenFone 2-series smartphones will reach two million units in May after their launch in March, indicated the sources, adding that the monthly shipments will rise to 2.5-3 million units in June.

Since Asustek has been increasing its orders to the upstream supply chain recently, it is able to acquire rather competitive prices for needed parts and components, said the sources.

In addition to using chipset solutions from Intel, Asustek has now expanded the chipset sources to include Qualcomm for its ZenFone products, added the sources.

However, whether Asustek is able to achieve its shipment goal for smartphones will still depend on its sales in China, commented the sources.

Meanwhile, Asustek is expected to ship 300,000-500,000 units of its ZenWatch- and VivoWatch-series smartwatches in 2015, the sources estimated.