An aircraft is being drafted in to help with an investigation to find out why oil has been washed up on stretches of the Lincolnshire coast.

The alarm was raised on Wednesday after the spongy oil lumps were found on beaches between Skegness and Mablethorpe.

The Maritime and Coastguard Agency said walkers made the discoveries which follow earlier finds last week.

It has been in the water for a very long time Mark Clarke, spokesman

Walkers have been warned not to go on beaches at present.

It is thought the oil may have been dumped at sea by tankers or may have risen from shipwrecks.

Agency spokesman Mark Clarke said: "What we will be doing is getting the coastguard out to evaluate how much of the stuff is ashore."

He said samples would be sent to a laboratory to see if it is from the same source as similar finds last week.

"It was very, very heavily watered which means it has been in the water for a very long time.

"That may mean that it was stuff that came out of a ship earlier, ie through tank washing or possibly up from a wreck - which of course we know there are many hundreds around that part of the coastline."