Shell CEO Wael Sawan has come under pressure over his strategy from within the energy company, after two employees issued a rare open letter urging him not to scale back investments in renewable energy, sparking an internal debate.

The open letter, posted earlier this month on Shell's internal web and seen by Reuters this week, comes after Sawan outlined at an investor day in June plans to slow investment in renewables and low-carbon business as part of a strategy to boost returns.

The company also split its low-carbon business and scrapped the role of global head of renewables. The holder of that position, Thomas Brostrom, who departed from the company, had spent less than two years in the role.