Int'l Paper in Bidding War for Champion

Sparking the move is a recent 20 percent slide in UPM's share price, which has caused the value of the UPM's all-stock offer to slip from $6.6 billion at the time it was announced to about $5 billion.

The possible bidding war is only the latest turmoil to hit the paper industry after a wave of consolidation deals swept over the industry a few weeks ago.