International Paper and Temple-Inland have agreed to extend the review period for their proposed merger until Jan. 27. The government's review was originally expected to conclude this week.

The companies also agreed to extend the outside date under their merger agreement from June 6 to June 28.

"We continue to cooperate with the Department of Justice and look forward to satisfying the closing conditions for the completion of this transaction," Sharon Ryan, IP senior vice president and general counsel, said in a statement.

IP spokesman Thomas Ryan said one shouldn't read too much into the extension agreement. "It's not uncommon for merging parties to agree with the Department of Justice to extend the statutory timeline," Ryan said.

Regulatory approval is the last hurdle before the deal is approved. If approved, the merger locks in IP's national dominance in corrugated packaging.

Shareholders of Temple-Inland approved the $4.3 billion merger deal at a special shareholders meeting earlier this month in Austin. Nearly 86.9 million shares of the Texas packaging and building products company, or 98 percent