Mattel Inc. says it has agreed to buy the company behind Thomas the Tank Engine and Bob the Builder for $680 million in cash.

Mattel, which owns Barbie, Hot Wheels and Fisher Price toys, is buying Hit Entertainment from a consortium led by private equity firm Apax Partners.

Mattel already markets many Thomas & Friends die-cast and plastic toys under a license that extends until 2014. Global sales of those toys are more than $150 million.

The acquisition will allow it to take over the wood license as well, when the license expires at the end of 2012. Sales of wood-based toys have been about the same as the die-cast and plastic business.

The deal is expected to close in 2012.