A billionaire cable television magnate is believed to have increased his landholdings in Maine substantially with the purchase of more than 53,000 acres of forest in the far northwestern part of the state.

John Malone, who already owns all the land around 5-mile-long Spencer Lake in Somerset County and property in Boothbay, has purchased the land, known as the Frontier Forest, west of Jackman and extending to the Quebec border, according to the Web site of the Maine Environmental Policy Institute.

A representative of Malone in Maine would say only that a group calling itself Frontier Forest LLC had purchased the land. Gary Bahlkow of LandVest, the company that oversees Malone’s Maine land, would not comment on who owns Frontier Forest LLC, but he declined to deny Malone was the purchaser.

Bahlkow said the land would continue to be managed as a working forest, and that public use would be “managed to avoid degradation of the resource.”

“No change of use is contemplated,” he said. “Nothing has changed except the ownership.”

Frontier Forest LLC was incorporated in the state earlier this month. The only information on file with the Secretary of State’s Office is that Wiscasset lawyer David Soule Jr. is the registered agent. He could not be reached for comment Friday.

The 53,524-acre property was owned by Great Eastern Timber Co. of Alabama and managed by Hancock Natural Resource Group of Boston. The transfer to Frontier Forest occurred May 16, according to the Somerset County Registry of Deeds. The purchase price will remain confidential until the sale is registered with the state’s Bureau of Taxation, which should occur in a couple of weeks.

LandVest had listed the property, which includes 11 ponds and three major streams flowing into the Moose River, for $17.8 million. While not divulging the purchase price, Bahlkow said it “reflects current market value.”

Malone created a controversy three years ago when he quietly purchased all 15,000 acres around Spencer Lake south of Jackman in two separate transactions for $13.5 million. Sportsmen were upset that the state had failed to secure a public boat launch on the lake and they feared the land would be put off-limits. Environmental groups feared it would be developed.

The land has remained open and has not been developed.

This time, the response to Malone’s purchase is more muted.

“I’m very confident that people will find him to be a very responsible landowner and steward,” said Kent Wommack, executive director of The Nature Conservancy’s Maine chapter.

The fact Malone bought the land is especially good news because a parcel of this size was well within reach of timber liquidators who would have taken all the wood and then subdivided the land for profit, Wommack said.

Malone joined the conservancy’s governing board a few months ago and has supported TNC projects around the country and in Maine, Wommack said.

As with Spencer Lake, the state had been interested in acquiring some of the Frontier Forest land, but a deal could not be struck, said Ralph Knoll of the Bureau of Parks and Lands. The state asked to buy thousands of acres adjacent to its Holeb public reserve lands, but Hancock Natural Resource Group did not want to divide up the land, Knoll said.

Then a conservation investor, who intended to sell some of the land to the state and put an easement on other portions, put in a bid for the land, but the offer was not accepted, Knoll said.

However, Knoll said he is not alarmed that Malone has bought the land.

“Is John a good steward of the land? The answer so far, with what he has done at Spencer Lake, is yes,” he said.

“From a conservation perspective, having Malone own it is a good thing,” Knoll added. He said the state still hoped to talk with Malone about the possibility of the state acquiring land or easements on the property.

Great Eastern Timber Co. also is trying to sell more than 32,000 acres of timberland north of Katahdin Iron Works and Gulf Hagas. The land, called The Katahdin Forest, is listed by LandVest for $11 million.

Asked if Malone or Frontier Forest is interested in purchasing that land, Bahlkow said: “I hope so.”

The state is not too interested in buying land in this area because it already owns the nearby 43,000-acre Nahmakanta public reserve land, Knoll said.

Malone, who lives in Colorado and owns a home in Boothbay, was ranked as the 90th-wealthiest person in America by Forbes magazine this year with a net worth of $2.1 billion.

His Forbes ranking has slipped in the last three years as he has given away more than $1 billion, much of it through the Malone Family Foundation, which supports education institutions. He recently gave $24 million to Yale University, his alma mater, for a new engineering building.

In 1998, Malone sold Tele-Communications Inc., the cable television company better known as TCI, to AT&T for $54 billion. He is now chairman of Liberty Media, AT&T’s cable television arm.