Jay Bhattacherjee, the chief executive of London-listed junior Aminex has stepped down with immediate effect due to health reasons, the company said on Friday.

Aminex appointed Tom Mackay as interim chief executive, with immediate effect.

Mackay, who joined Aminex in September 2014, is currently the senior non-executive director on the board.

Aminex said it will commence the process for the recruitment of a new chief executive “in due course”.

John Bell, chairman of Aminex, said: “We are all very sorry that Jay has had to step down at short notice due to a medical condition, which requires immediate attention.

“Since he joined the company in 2013, he has overseen a number of projects, most notably the progress on the Ntorya field, and has been a well-respected colleague. We wish Jay all the very best as he focuses his efforts on his health in the coming months,” Bell said.

Upstream caught up with Calgary-born Bhattacherjee recently where he talked about his upbringing and progress through the industry.

Aminex holds assets in two basins in Tanzania, near installations held by ExxonMobil, Shell and Anadarko.

With infrastructure already in place, and a recent farmout to Oman’s Zubair Corporation, Tanzania and gas-rich Ruvuma is the company's core focus.