After having their initial bid of 2.2 billion rejected by Associated British Ports, US investment bank Goldman Sachs consortium of investors has raised its offer to 2.5 billion.
The ADP regarded Goldman Sachs original offer as wholly inadequate, but is considering the increased bid.
If approved, the deal would mark the third of Britains major ports to be bought out by foreign investors.
Ports business has seen increased investor interest lately as world trade continues to boom, bringing in a steady profit income.
In 2005, Peel Ports bought out Mersey Docks & Harbour for GBP771 million, and Dubai Ports World picked up P&O for GPB3.9 billion.
Goldman Sachs offer comes to roughly 14 times ADPs entire 2005 gross earnings, calculating at GBP8.1 per share.
The companys current stock market values equate the offer to GBP7.5 per share.