A radioactive leak has been found at the former Dounreay power station.

It is understood liquid effluent leaked inside a treatment facility, but was detected and quickly contained.

A spokeswoman for the Scottish Environment Protection Agency (Sepa) said no material had been released into the environment and that the leak was "minor".

She said the next stage would be a clean-up operation and an investigation into how the leak had occurred.

Dounreay's nuclear reactor was shut down in 1994 and work to decommission the site in Caithness has been under way since then.

It was the only plant in Britain to use liquid metal instead of gas or water in the cooling circuits.

The Sepa spokeswoman added: "As far as we are aware there is no cause for concern."