OMI Corporation has announced it has reached an agreement in principle with the US Department of Justice to pay a $4.2m fine and serve a three-year probation over oily water dumping.

There has been a string of prosecutions by US authorities involving such incidents but OMI is one of the biggest names to have been caught in the net.

In a separate case in Portland Fairmont Shipping has pleaded guilty to a similar offence and will pay a $450,000 fine.