Magnitude 6.1 earthquake strikes off Tonga

A magnitude 6.1 earthquake has struck under the sea 170km west of Neiafu in Tonga at a depth of 10km, according to the US Geological Survey.

The survey revised down an initial reading of 6.4. The quake struck in the early hours of Monday Sydney time.

There was no tsunami warning in effect from the Pacific Tsunami Warning Center.