Production of Apple's new MacBooks is ramping up, causing labour shortages in the supply chain.

That's according to DigiTimes, which reports that Apple's manufacturers have been receiving increasingly large orders for the new MacBook Pros, which are expected to be announced at the Worldwide Developers Conference in June.

DigiTimes claims that sources from the upstream supply chain have said that some suppliers have been forced to outsource their orders in order to meet Apple's difficult shipment schedules.

The report suggests that the new MacBooks will hit the shops in July, with component shipments expected to reach their highest in June.

DigiTimes suggests that Apple's year-on-year MacBook shipments could increase by up to 50 per cent, to 16.24-19.2 million units in 2012.

The new MacBook Pros are expected to have Intel Ivy Bridge processors, a feature that Mac users believe will be the 'killer feature' of the new product. They could also be made with Liquidmetal, and be radically redesigned, with a thinner, more Air-like profile.

Read more about Apple's new MacBooks here.