Two lawsuits have been filed over a gob of toothpaste.

Escalating a battle between two of the world's biggest toothpaste makers, Colgate-Palmolive Co sued GlaxoSmithKline Plc in Manhattan federal court, seeking a court order that its packaging for Colgate toothpaste does not infringe trademarks held by the maker of Aquafresh.

A few hours later, Glaxo filed its own lawsuit against Colgate in the same court, seeking to stop the infringement of its own marks.

Each company is seeking the right to depict, and to stop the other from depicting, a nurdle, a wave-shaped toothpaste blob that sits on a toothbrush head.

In its 76-page complaint, Colgate said it recently launched in the United States a toothpaste whose packaging superimposes the words Triple Action -- suggesting cavity protection, fresh breath and whiter teeth -- on a blue, white and green nurdle.

But it said Glaxo, which uses the Triple Protection phrase on Aquafresh products, filed a trademark application for the nurdle design regardless of color, prompting Colgate to sue to enforce its rights to use the nurdle.

This new application is a blatant shot across Colgate's bow, as Glaxo did not file this application until after Glaxo had already complained about Colgate's nurdle design, Colgate lawyer Brendan O'Rourke of Proskauer Rose LLP wrote.

Colgate is deeply concerned that Glaxo desires to stifle competition in the marketplace through over-broad assertions of trademark rights, he added.

Meanwhile, in its 45-page complaint, Glaxo accused Colgate of adopting various nurdle designs and the Triple Action mark in an effort to trade off the commercial magnetism of its own packaging, which has included a red, white and blue nurdle.

Glaxo introduced its nurdle around 1987 and believes Colgate's use of a competing nurdle causes immediate and irreparable harm by creating a strong likelihood of confusion among consumers, Glaxo lawyer Lisa Pearson of Kilpatrick Stockton LLP wrote.

Colgate asked the court to declare that its Triple Action phrase and nurdle are not confusingly similar to Glaxo's Triple Protection phrase and nurdle design in other colors. It also seeks to cancel Glaxo's Triple Protection and nurdle trademark registrations.

Glaxo asked the court to stop Colgate from using any nurdle design similar to its own and also the Triple Action phrase. It also seeks a variety of damages including punitive damages.

Colgate is based in New York. Glaxo is a British company that has U.S. offices in Philadelphia.

In Thursday trading in New York, Colgate shares fell $5.74, or 6.8 percent, to close $78.12, while Glaxo shares fell 28 cents, or 0.8 percent, to $35.16.

Separately, Colgate posted lower-than-expected second-quarter sales on Thursday.

The cases are Colgate-Palmolive Co v. GlaxoSmithKline LLC, U.S. District Court, Southern District of New York, No. 10-05728 and GlaxoSmithKline LLC v. Colgate-Palmolive Co in the same court, No. 10-05739.

(Reporting by Jonathan Stempel; editing by Gerald E. McCormick, John Wallace and Andre Grenon)