InterOil (NYSE:IOC) founder and CEO Phil Mulacek is retiring effective April 30, but will will continue as a director and will provide advisory services to the oil exploration firm, the company announced today.

With a global search under way for a replacement, InterOil Chairman Gaylen Byker will assume Mulacek's duties on an interim basis beginning May 1.

Mulcacek, who has more than 25 years experience in oil and gas exploration and production, founded InterOil in 1997 and served as the company's board chairman until July, 2, 2012. Byker stepped in as chairman at that time.

Mulacek is also the founder and president of privately held Petroleum Independent & Exploration, which was established in 1981 and led the development of InterOil's refinery and the commercial activities necessary to secure the refinery's economic viability.

Byker is quoted as saying, "Mr. Mulacek pioneered InterOil's exploration activities in the Gulf Province of Papua New Guinea that resulted in the discovery of the Elk/Antelope and Triceratops fields which contain in total a best case estimate of 1.6 billion BOE of contingent resources. This is an unusual feat, seldom accomplished in any field."

InterOil's assets consist of petroleum licenses covering about 3.9 million acres, an oil refinery, and retail and commercial distribution facilities, all located in Papua New Guinea.