Wellington, Sep 25: A powerful 6.3-magnitude earthquake struck off Tonga early today but there was no threat of a tsunami, US seismologists said.

The offshore quake hit at 7:07 am (local time) and was centred around 124 kilometres northwest of Tonga, the US Geological Survey (USGS) said on its website. The Hawaii-based Pacific Tsunami Warning Centre said there was no tsunami threat. (ALSO READ: Strong 6.3 earthquake rattles southern Philippines: USGS)

In its preliminary impact assessment, the USGS said there was a low likelihood of casualties and damage.