Apple has reportedly stopped placing component orders for its Mac series products recently and related upstream suppliers so far have not yet received any word about when the US-based vendor will resume its orders, according to sources from the upstream supply chain.

The suppliers originally expected to finish digesting their Mac inventories in April, but are now stranded waiting for further instructions from Apple.

The sources revealed that Apple's Mac orders to the supply chain dropped to almost nothing after the Lunar New Year holidays. Apple had high hopes for its Mac product lines and placed aggressive orders at the end of 2012; however, the company is now badly affected by the decision.

Since Apple hardly mis-estimates its shipment forecasts, the sharp order drop may imply that Apple has underestimated the PC industry's weak status and its iPad products are affecting the PC industry more seriously than it expected.

In the past, Apple usually gave its suppliers its shipment forecast for the upcoming quarter (12 weeks), but the company did not provide a shipment forecast for the second quarter and some suppliers are concerned that shipments may not resume until late May.