New Zealand Civil Defence says there is no tsunami risk from a magnitude 6.4 quake which struck near the Kermadec Islands on Saturday afternoon.

The National Emergency Management Agency was advising people in coastal areas to stay out of the water, stay off beaches, and to not go sightseeing while it was assessing the risk of a tsunami.

"Based on current information, the assessment is that the earthquake is unlikely to have caused a tsunami that will pose a threat to New Zealand."

The earthquake struck at 3.46pm in the region, northeast of New Zealand, about halfway to Samoa, and was 33km deep according to NEMA.

The original alert was issued at 4.07pm.

A second 5.3 magnitude earthquake struck near the original at 4.01pm.

Civil Defence says local flooding is not expected and people don't need to evacuate unless directly advised by local authorities.