CORPUS CHRISTI, United States (AFP) - Officials in Texas said on Saturday (Aug 26) they plan evacuate 4,500 inmates from three prisons over fears they could be hit by flooding triggered by Hurricane Harvey.

The Texas Department of Criminal Justice said three detention facilities - Ramsey, Terrell and Stringfellow - would be evacuated as a precaution, as waters rise from the nearby Brazos River.

Authorities said the inmates would be transferred by bus beginning to facilities in another part of the state.

The evacuation order was issued as Texas and parts of Louisiana faced the threat of historic flooding from Harvey, which roared ashore early Saturday as a category four hurricane.

The storm - the most powerful to hit the US mainland in over a decade - slammed into Texas, destroying homes and other buildings, forcing tens of thousands of residents to flee.

A vast area of Texas faces potentially devastating floods from the storm, which was could dump as many as 100cm of rain in some regions.