A 2014 Treaty of Waitangi settlement deadline is unrealistic and jeopardises the entire process, Labour's Treaty negotiations spokesman Michael Cullen said.
Labour set a 2020 deadline and National had originally said it wanted to settle all historic Treaty claims by 2010, before extending it to 2014.
Last week, the Justice Ministry said it did not have enough resources to meet the 2014 deadline and would talk to the Justice Minister about it.
Dr Cullen said there had been "mixed reports" over whether the deadline would be extended in light of the ministry's claims.
"If the Government proceeds with an artificial deadline, it risks upsetting the whole process and could create a situation where settlements are neither fair, nor final.
"There is too much at stake here to play smoke and mirror games."
Treaty Negotiations Minister Chris Finlayson said the Government had never set a concrete deadline but was working towards completing all settlements by 2014.
That was still the policy, he said.
Should there be outstanding claims in 2014 the minister would not impose a settlement because he wants all settlements to be "just and durable".
"If it happens that a settlement remains unresolved in 2014 and will spill into 2015 or 2016 then that's the way the cookie crumbles.
"The Government will not try and force settlements unnaturally by trying to impose top-down settlements on groups of iwi and hapu."
The organisation of claimant groups and funding for the Office of Treaty Settlements were key factors in reaching the 2014 "ambitious target".
The Waitangi Tribunal was analysing new and existing claims in order to prioritise.
The Office of Treaty Settlements' work increased by 39 percent from 2003-4.
