The battle between book-selling powerhouse Amazon and publishers is heating up as Wall Street nudges the online behemoth to squeeze even more money from sales.

The latest skirmish has Amazon pulling nearly 4,000 titles from its catalog of downloads, all of them published by the Independent Publishers Group (IPG).

Word is that when IPGs contract with Amazon came up for renewal, the terms were so draconian that the publisher balked.

“They decided they wanted me to change my terms,” said Mark Suchomel, president of the Chicago-based IPG told the New York Times. “It wasn’t reasonable. There’s only so far we can go.”

Amazon’s desperate to make sure its Kindle device dominates the e-books market, and keeping prices of titles low is one way to ensure that’s likely. But publishers, already squeezed by the dramatic changes in their industry, are clinging to a soft life preserver.

Tags: Amazon, Independent Publishers Group, IPG, Kindle