LONDON, Feb. 17 (Xinhua) -- A minor earthquake has struck southwest Britain Saturday, reported local media.

Early data from British Geological Survey (BGS) measured the quake to be 4.4 magnitude.

The BGS said such an event only occurs in Britain about every two to three years.

The epicentre was approximately 20km north-east of Swansea and at a depth of 7.4km, according to BGS.

A spokesman for the BGS said: "It was a reasonably-sized earthquake. This earthquake has been felt across a large area of Wales and England with the furthest reports so far from Birmingham and Devon. This is the largest earthquake in mainland UK since the 5.2 magnitude Market Rasen earthquake in 2008."

Thousands reported feeling the tremor from Cornwall to Liverpool, and there's no report of casualties by far.

Cardiff police tweeted that there was no need to contact emergency services, hoping to set people's minds at rest.

According to local newspaper Telegraph, the most serious earthquake in Britain was the one that hit the Colchester area in 1884 and damaged more than 1,000 buildings.