An explosion at one of two factories that make Apple's new iPad 2 highlights the risks of a global manufacturing strategy that has cut costs but concentrates production in a few locations.

Foxconn Technology Group, the contractor that manufactures Apple's iPhones and iPads, said Friday's blast in the western city of Chengdu killed 3 employees and injured 15. The Taiwanese company said production was suspended but did not respond to questions on Monday about how supplies of iPads might be affected.

Estimates by industry analysts of the impact on iPad production ranged from minimal to up to 2.8 million units in lost output. That is equal to just over half the number sold in the first three months of this year but Apple says sales are so strong it already is struggling to keep up with demand.