A strong 6.1-magnitude earthquake struck early Monday in the Mediterranean between Morocco and Spain, the US Geological Survey said.

The shallow quake hit at 4:22 am (0422 GMT) 62 kilometres (39 miles) north of the Moroccan city of Al Hoceima and 164 kilometres east-southeast of Gibraltar, USGS said. It was followed by a 5.3-magnitude tremor.

In its initial assessment of the quake's impact, USGS said there was "a low likelihood of casualties and damage".

In February 2004 a strong 6.3 earthquake that hit near Al Hoceima killed 631 people.