A joint commitment by four political parties to re-enter the Pike River mine by the end of next year is nothing more than a political stunt, the government says.

Families of the 29 victims of the 2010 disaster are applauding the commitment by Labour, the Greens, the Maori Party and United Future.

But Environment Minister Nick Smith says a cross-party statement doesn't alter the risks involved.

"It is a hollow political stunt for parties to promise a manned re-entry of the mine by the end of 2018," he said.

"This political commitment could not be done under New Zealand's workplace laws."

The four party leaders signed the agreement on Tuesday.

It commits them to establishing an agency to take ownership of the mine from Solid Energy within the first 100 days of a new government.

The agency would then be directed to carry out a plan for complete recovery of the drift - the tunnel that leads into the mine - by the end of 2018 so that human remains and evidence can be collected.

The government is working with the families on unmanned re-entry carried out by robots.

The equipment is due to arrive in November and unmanned re-entry is expected before the end of the year.

NZ First leader Winston Peters, who has previously committed his party to re- entry and has offered to be the first man in, also says the commitment is a publicity stunt.

"I don't like seeing people using death and misery for political reasons," he said.