Twenty-nine men died in a series of explosions which started on November 19 while working underground at the Greymouth mine.

Whittall is now facing 12 criminal charges in relation to the tragedy, which he plans to “vigorously” defend.

Despite not attending the anniversary service, a statement from his lawyers said it would be a tough day for the former chief executive.

“It is an anniversary that will be a difficult time for so many people; no less so for Mr Whittall,” it said.

“Mr Whittall does not wish attendance by him at Saturday’s memorial service in Greymouth to take anything away from a day that should properly be focused on those who lost family members on 19 November 2010,” the statement said.

“He will therefore be marking the occasion privately in Wellington.”

Whittall again expressed his “deepest, ongoing sympathy” to the families of those who died.

Whittall started at Pike as the general manager in 2005 and became chief executive in mid-September 2010, roughly two months before the first underground explosion rocked the mine.

According to local news service TVNZ, the ceremony is to be held at Rugby Park in Greymouth tomorrow at 2.45pm.

The service will end in silence at 3.44pm to mark the time of the first explosion.

Local reports said several thousand people were expected to attend the memorial, including New Zealand Prime Minister John Key who will be one of the speakers.

A private ceremony is expected to be held earlier for the family members of the victims.