The chair of Sellafield Ltd is stepping down to take a role with a major oil and gas company – sparking a hunt for his replacement.

Tony Fountain has accepted an offer to become the chair of Essar Oil and will step down from his role at Sellafield Ltd later this month.

Mr Fountain’s departure will come halfway through a three-year tenure in the hot seat.

He took up the role in April last year when Sellafield Ltd became a wholly owned subsidiary of the Nuclear Decommissioning Authority (NDA), taking the management of the site away from international consortium Nuclear Management Partners.

Nigel Smith, a senior independent non-executive director with Sellafield Ltd, will cover the role in the interim until a replacement is found by the NDA.

An NDA spokesman said the recruitment process would involve a “market search as well as selection interviews and assessments”.

They would not comment on the remuneration package that would be available to the successful candidate.

Mr Fountain, who was unavailable to comment, served a two-year stint as chief executive of the NDA between 2009 to 2011, before leaving for a senior role at Mumbai-based Reliance Industries.

His new company, Essar Oil, also based in India, is involved in the exploration and production of oil and natural gas, refining crude oil and marketing petroleum products.

Prior to joining the NDA, he held a number of senior roles at BP.

David Peattie, NDA chief executive officer, said: “On behalf of the NDA, I would like to offer my sincere thanks to Tony for his excellent leadership and contribution to the clean-up mission at Sellafield.

“We wish him every success in his new role.”

Mr Fountain will chair his last Sellafield board meeting at the end of the month.

According to the NDA, the chair’s role is to “lead the board of non-executive and executive directors in driving safe and secure progress and value for money in the delivery of the mission at Sellafield”.