Last week, the Committee for Energy Resources apparently a new public interest group, sprang into being with a flurry of advertisments in The Wall Street Journal, The Washington Post, the Los Angeles Times and The New York Times, attacking Mobil Corp. for its plan to buy Irvine Co., a land-rich real estate concern.

The committee didn't say much about itself, listing only a Washington address and a man named G.H. Hunt as its chairman. It took a very public-spirited tone in its attack on Mobil, asking in its ads, "Why is Monbil Corp. investing substantial cash reserves in real estate development ventures throughout the U.S. via their foreign based subsidiary?"

The ads went on to suggest that Mobil should be putting its money into domestic energy deveopment rather than real estate, and urged readers to "contact your Congressman or Senator now for appropriate government action."

Despite the tone of the ads, the Committee for Energy Resources isn't just a public interest group, it is associated with the interests of Donald Bren, the leading partner in Taubman-Allen-Irvine Inc., an investor group competing with Mobil for the right to buy Irvine.

Hunt, The Wall Street Journal learned, is an employe of Bren Co., a successful land-government concern in Southern California owned by Donald Bren. Bren's brother, Charles, paid for at least one ad, representing himself as director of marketing for Bren Co. and Mr. Hunt as an attorney. (Hunt says he isn't an attorney, but a law student.)

Taubmam-Allen-Irvine Inc. was formed recently to bid for the shares of Irvine Co. Its partners, in addition to Brem, include Detroit real estate developer A. Alfred Taubman, New York investment banker Charles Allen Jr., Detroit industrialists Henry Ford II and Max Fisher, and Irvine heiress Joan Smith and her first cousin, Linda Gaede. In March, it weighed in with a $302.9 million all-cash offer for Irvine's 8.4 million shares, $20.9 million above an existing $282 million all-cash offer by Mobil. Monday, Mobil announced it raised its offer to $307 million.

The committee's ads, which began running April 28, aroused the curiosity of Mobil. It attempted, apparently unseccessfully, to learn more about the Committee for Energy Resources from the newspapers that ran them and from Morris Rosenbloom, who runs a public relations firm, American Surveys Co., in Washington, D.C. The committee had given American Survey's address as its own and told the newspaper that Rosenbloom was its contact.

At a news conference in Houston, following Mobil's annual meeting yesterday, chairman Rawleigh Warner Jr. was asked about the ads and said he strongly suspected the committee the committee was connected in some way to the Taubman-Allen Irvine group.

Later in the day, when Mobil learned that the Brens were behind the ads, it reached angrily. One spokesman immediately gibed, "Donald Segretti lives!" - referring to the dirty trickster of the Nixon administrations. In a prepared statement issued an hour later, Mobil said, "If these reports are correct, we are shocked and dismayed, especially in view of the stature of the parties involved in the other group bidding for the Irvine Co.

In Los Angeles, Hunt denied that the committee's ads were dirty tricks designed to influence the bidding war for Mobil. He said three other people in addition to the Brens helped pay for the ads, but declined to confirm or deny that the Brens picked up men of the tab.

Hunt said the committee is registered with Congress as a "public interest lobbying group" and would disclose the sources of its income when required to do so.

Bren Co. said Donald and Charles Bren weren't available for comment.