Mr Dunne said he had negotiated with the Government over the definition of "mass arrival"and would now support the bill, which will go through Parliament under urgency.
Originally the bill defined mass arrival as more than 10 people.
"The Government has agreed to drop what we considered was the far too harsh definition of a mass arrival as more than 10 people.
"It has now agreed to support a supplementary order paper that I will move to define a mass arrival as being more than 30 persons," said Mr Dunne.
He was pleased a compromise had been reached with Immigration Minister Michael Woodhouse.
Prime Minister John Key in February announced a deal reached with Australian counterpart Julia Gillard that would see New Zealand accept 150 Australian-approved refugees each year.
In return Australia would help New Zealand process a mass arrival at its offshore centres in Nauru and Papua New Guinea.
- Kate Shuttleworth of APNZ
