‘Nic and I are lockstep’: Twiggy speaks about split for first time

Andrew Forrest has opened up about his separation from wife of 31-years Nicola Forrest, in his first interview since the billionaires split.

The Fortescue Metals Group boss, often referred to as Twiggy, also revealed the reason behind the shock departure of CEO Fiona Hick just six months into the job.

In an interview on the sidelines of a business summit to address climate change, the mining magnate was asked whether Hick left of her own accord or if she was pushed out.

"Fiona was given a choice to make and she chose, so I'd say she wasn't pushed," Mr Forrest told 9News.

Her shock resignation was revealed 48 hours after FMG's lavish 20-year bush bash at a mining camp — a party Hick attended.

"We have a full and very green agenda," Mr Forrest said, after addressing the Boao Forum for Asia in Perth.

"I think it's going to be great for shareholders, it's absolutely essential for the environment, and you either get with it or you don't, it's just as simple as that."

The Fortescue boss wouldn't be drawn on whether Hick was not aligned with that agenda.

"I'm not going to answer any further; you can come back 300 times you'll get the same answer," he said.

Twiggy's empire lost another executive on Tuesday, with the list of high profile exits growing as his core mining business adds clean energy to the mix.

But he's not worried by the departure of Hick, Guy Debelle, Felicity Gooding and Ian Wells.

"I said at the start in this transition 12 people would change in the C-suite at this company we're nowhere near 12 yet, we are going to see further change if it's required," he told 9News.

"There's no better-governed company in this country and there's been no better performance by any company for total shareholder returns for decades."

It's been a year of change for the mining magnate, dipping from second place in the AFR's Rich List to 13th.

He was overtaken by his wife when the pair announced they were splitting up — and splitting assets.

"Nic and I are good mates, we speak all the time she's a fantastic lady," he told 9News.

"We made the call that it was better for everyone if we didn't live right on top of each other but we still absolutely support each other."

He gave reassurances to shareholders that the former couple's new arrangement wouldn't impact the business.

"Nic and I are lockstep on that — we are completely committed to Fortescue, to Tattarang, all the objectives of Mindaroo, we are completely united," he said.

Wednesday's trade forum at the Ritz attracted a range of heavy hitters from across Asia.

Andrew warned attendees about climate change and highlighted the potentially lethal combination of increasing heat and humidity.