"By around 2008 there is a real risk there will be insufficient gas to fire our existing suite of power stations," he told Reuters on the sidelines of an energy conference in New Zealand.
"If we do nothing we won't have enough electricity towards the end of the decade."
With the cornerstone Maui gas field due to run dry in 2007 and around a third of New Zealand's electricity generated by gas-fired power plants, Griffiths said the first priority should be to hunt for domestic gas and put out the challenge to smaller explorers.
"Four million people scattered over an area the size of Oregon in California just doesn't really create much of a prize for an organisation of BP's size and so smaller niche players and niche fields are what are needed."
He said the government had made policy changes to encourage exploration that did not go far enough and proposed it make the upfront investment to lure explorers.
"We need to put some money into it. Giving people tax breaks and royalty breaks -- you have to have actually found something in order to collect any of that."
BP, which has had a presence in New Zealand for 58 years, pulled out of the upstream sector in the late 1980s. It currently has a 23 percent stake in the country's only oil refinery. Royal Dutch/Shell, the only oil major involved in exploration in the country, said last year it would scale back spending in New Zealand after failing to discover significant new reserves in the past two years.
Griffiths flagged the need for more investment in plant capacity, saying the country's electricity demand was growing at two-to-three percent a year, a rate that would support a new 350-megawatt (MW) power station being built every two-to-three years.
GREEN POWER & LNG With no certainty domestic gas finds can fill the gap quickly enough, Griffiths said New Zealand must look more closely at "green power" options and liquefied natural gas (LNG).
"Geothermal power production for example, could buy New Zealand more time. "There is somewhere in the region of 300 to 500 megawatts of geothermal power which is undeveloped here."
Renewable energy comprises around 22 percent of the country's current energy mix. He said LNG would offer the most certainty and BP would also have a vested interest in seeing it developed. BP would be keen to supply LNG as well as provide technology and shippers but said those wanting the gas might not want to be tied to one supplier, he said.
"How long can you continue to try and find gas before you really have to bank on some certainty, which is what LNG could give New Zealand -- certainty. "There definitely would be gas available for New Zealand in unlimited quantities at a known price, it would be a higher price for sure, but there would be gas and it would be available."