One new confirmed case and a second probable case of measles, have been identified in the Waikato

Both cases are young children, and their families and close contacts are being supported by local public health services, with those most at risk in quarantine.

The cases spent time in Auckland, Waikato and Tauranga, likely during their infectious period, between March 23 and 26.

Health New Zealand's Dr William Rainger, says with no connection to overseas travel, and the original source not known, it's suspected they caught measles from someone else in the community.

He says there's a real concern and high risk, that others could be infected and may not know it yet, so people should contact Healthline urgently if they have symptoms.