As the Pike River protest builds, mine managers and the Government are facing further criticism.

It's the 18th day picketers have spent at the mine portal pleading for State Owned Enterprise Solid Energy to stop sealing it.

Yesterday there were more protestors than ever - with 24 on site.

After seeing the families on television, writer Dame Fiona Kidman and her husband flew down from Wellington to join today's protest.

Dame Fiona is taking a direct swipe at the Prime Minister as she joins the Pike River protest.

She said she was driven by anger, and she has a direct message for John Key.

"Look, you made a promise, this is your moment to keep it. Otherwise you're legacy will be somebody who has broken a promise."

She said it's a travesty to seal the mine and ignore evidence showing it's safe to enter.

"We're family people and if those were my sons or father, or people that I loved, I would want a lot of people standing up and saying this is not good enough."

The families want an attempt to retrieve any bodies and evidence inside.

Dame Fiona said seeing them on the news stirred her into action.

"I said to Ian 'I think that we should be there'. I said, 'should we go?' We shouldn't just leave the people of Greymouth to bear this alone."