VIENNA, Sept 18 (Reuters) - LafargeHolcim LHN.S is considering withdrawing from several markets as part of its efforts to make last year's mega-merger a success, Chairman Beat Hess told weekly Sonntagszeitung.

"We will be present in less countries for sure," Hess was quoted as saying. The sale of operations in several countries was an option, he said.

The world's largest cement group, created by a merger between Frances's Lafarge and Switzerland's Holcim, generates 80 percent of its operational earnings before taxes, depreciation and amortisation in 25 countries, the paper quoted Hess as saying.

He said there was "much potential for improvement" in another 25 countries. "Either we succeed in strengthening these operations through targeted investments or we have to see whether other owners could do better."

For the remaining 40 countries the Switzerland-based firm operates in, the question was how to reach the target to earn its capital costs in the foreseeable future and "whether it would not be better to invest elsewhere the proceeds coming from a sale."

The company has already exceeded its 2016 goal of making divestments worth 3.5 billion francs and said in August it had extended the programme to 5 billion francs by the end of next year.

In addition to the 250 jobs which are shed as part of a reorganization of global functions the group will cut more jobs in its country organisations and it could close more plants, the paper quoted the chairman as saying.

"In big markets, where both Lafarge and Holcim were present, we still have to adjust structures," the chairman said.

(Reporting by Kirsti Knolle; Editing by Toby Chopra) ((kirsti.knolle@thomsonreuters.com; +43 1 53112 255; Reuters Messaging: kirsti.knolle.thomsonreuters.com@reuters.net www.reuters.com ))