Oil leak like no other

Hi guys.
Yesterday I was driving my 300 tdi discovery when I noticed the oil light come on so I investigated lifted up the the bonnet and to my horror oil everywhere so spanners out and checked out all the usual suspects. Everything was tight and no leaks from any joints so I filled up and started the engine as I'm looking I found the leak its if you facing the drivers side wing looking at engine if you follow the second head bolt (from filler cap going towards back of engine) down on to the engine block there is a machined hole it's coming from there in fact there are three holes in a row can any one tell me why the car is leaking oil from here and what are these holes here for and should I block it up thanks .
John

sounds like the filter position.

pic would help.

The Mad Hat Man said:

sounds like the filter position.

pic would help.

Click to expand...

His question has been answered on the 'introduce yourself' bit.

The hole in question is the top part of engine just below the head there's a brown strip right hand side of that strip is a bung it's leaking from there mine hasn't got a bung on it never did since I've had it I've had a couple of answers but just wondering if any one has had this before and what they did to cure it.