A platoon of New Zealand Army troops has left New Zealand to try to bring calm to the troubled streets of East Timor.

Forty-two troops flew out of Christchurch on an RNZAF Hercules C130 about 12.30pm today bound for Townsville, Queensland, to await final deployment to East Timor.

The soldiers have been on stand-by to go for more than a week, but were only given notice of the trip last night.

There was an emotional farewell for some of the troops as they had only received the call to duty at 9.30am today. Around 30 family members were at the airport.

The deployment came in response to a deteriorating security situation there which has seen chaos and murders on the streets of the capital, Dili.

Details were emerging this morning of a massacre in which the United Nations said East Timor soldiers opened fire on unarmed police, killing nine officers and wounding 27 other people.

The New Zealand troops will be away for no more than a month because they are not been fully innoculated against tropical diseases.

Platoon leader Lieutenant John Lawrey said the troops' job would be to provide security as called upon by the Australian-led intervention force.

Private Katiama Niwha's excitement at travelling to East Timor was tempered by the sadness of having to leave behind his partner Kaycee Tipene-Thomas and five-month-old son Tekohu.

"I don't know what to expect, but I'm ready to go. This is why I joined the army," Private Niwha said.

Ms Tipene-Thomas was philosophical about her partner having to go. "At the end of the day, it's his job. I knew what I was getting myself into," she said.

Communication between East Timor and New Zealand was expected to be limited.

"If I don't hear from him, I'll know he's all right," Ms Tipene-Thomas said.

Prime Minister Helen Clark announced early today that New Zealand would join the peacekeeping effort in East Timor (Timor Leste). The National Party backed the deployment.

Helen Clark said New Zealand's force would work with the Australian military and both countries were likely to operate under the same rules of engagement.

That means New Zealand troops could be under a "shoot to kill" policy. Helen Clark expected more details on the nature of New Zealand's role within 24hours.