By Liana B. Baker and Jessica DiNapoli

(Reuters) - U.S. brand management company Iconix Brand Group Inc <ICON.O> is exploring a sale of its majority stake in Peanuts Worldwide LLC, which owns the rights to cartoon strip characters Snoopy and Charlie Brown, according to people familiar with the matter.

The move sent shares of Iconix up more than 5 percent. It comes three months after U.S. insurance company MetLife Inc <MET.N> dropped the Peanuts characters it had been using as mascots for more than 30 years - a blow to debt-burdened Iconix.

The characters, which include Lucy, Peppermint Patty and Pigpen, have attracted the interest of Chinese companies as well as other investors keen to snap up U.S. media and licensing assets, the people said this week.

Created by Charles Schulz and licensed in over 100 countries, the characters generate about $30 million in 12-month earnings before interest, taxes, depreciation and amortization, the people added. They declined to comment on the expected deal valuation.

Besides Peanuts, Iconix is also looking to sell its Strawberry Shortcake brand, which is based on a character that rose to fame in the 1980s as a doll for young girls, the people said. They asked not to be identified because the matter is confidential.

The New York-based company is working with investment bank Guggenheim Partners LLC on an auction process to sell the brands, the people added, cautioning that there was no certainty that any deal would occur.

Iconix did not respond to a request for comment, while Guggenheim declined to comment. Iconix shares jumped 5.2 percent at $10.36 on the news in New York on Tuesday afternoon, giving the company a market capitalization of close to $600 million.

While MetLife will stop flying blimps featuring Snoopy this year, Peanuts has agreements with brands such as chocolate maker Nestle SA <NESN.S>, stationary company Hallmark Cards Inc, and retailer Zara, according to a regulatory filing by Iconix.

In 2015, Twenty-First Century Fox Inc <FOXA.O> released The Peanuts Movie, which was nominated for a Golden Globe award and grossed $246 million worldwide, according to Box Office Mojo, a website that tracks the revenue that movies generate.

Peanuts' largest international market is Japan, where a new Snoopy museum opened last year, according to the Iconix filing. The company renewed a long-standing contract to air the popular Peanuts holiday TV specials on U.S. network ABC in 2014 for five years.

Initially called "Li'l Folks", the comic strip was renamed "Peanuts" in 1950, when it became syndicated in seven newspapers, according to the Charles M Schulz Museum website. Schulz passed away in 2000.

Iconix, which also owns clothing brand Joe Boxer and outdoor wear brand London Fog, purchased an 80 percent stake in Peanuts in 2010 from U.S. media company E.W. Scripps Co <SSP.N> in a deal valued at $175 million.

The remaining 20 percent in the company is owned by Charles M. Schulz Creative Associates, which is controlled by the Schulz family.

Iconix sold another flagship brand, the Sharper Image, last year to its biggest licensee, ThreeSixty Group Inc, for $100 million. The transaction was used to pay down some of Iconix's debt, which totaled $1.29 billion as of the end of September.

Last year, Iconix said it would help develop and produce a new animated series based on Strawberry Shortcake. Iconix acquired the brand about two years ago for $105 million from greeting cards maker American Greetings Corp.

(Reporting by Liana B. Baker in San Francisco and Jessica DiNapoli in New York; Editing by Edwina Gibbs and David Gregorio)