"We are all very sorry that Jay has had to step down at short notice due to a medical condition which requires immediate attention,” said John Bell, Aminex's chairman.
Bell added: “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 focusses his efforts on his health in the coming months."
Tom Mackay has been named as interim chief executive and the company intends to start a recruitment process in due course.
Mackay has been with the company for nearly five years, having joined the board in September 2019 as a non-executive director.
Alastair Ferguson, chief executive at Solo Oil, Aminex’s partner in Tanzania, said: “We wish Jay all the best with his health issues and hope for a speedy recovery.
“We look forward to working with Tom in the interim and then with the permanent CEO as we continue to forge a closer JV relationship with Aminex that benefits Solo's investments in Ruvuma and Kiliwani North."
Shore Capital analyst Craig Howie, in a note, meanwhile said: “Aminex’s board will commence the process for the recruitment of a new CEO in due course and, in the meantime, we join the company in wishing Mr Bhattacherjee all the very best as he focuses on his health in the coming months.
“We continue to highlight the improved risk profile that we expect to result from the transformational Zubair farm-out deal in Tanzania, which will see Aminex carried through a material work programme and straight into production at the flagship Ruvuma project.”
In Friday’s deals, Aminex shares were down 1.89% changing hands at 0.88p.
-- Updated to include analyst comments and share price details --