Italian oil and gas company Eni has bought upstream assets in the Gulf of Mexico from Dominion Resources for $4.757 billion, Eni said in a statement on Monday.
Eni said the acquisition would boost its production in the area to more than 110,000 barrels of oil equivalent per day (boepd) in the second half of 2007. In the period from 2007-2010, production from the new assets would average more than 75,000 boepd.
Eni, Europe's fourth-biggest oil company by market value, said included in the purchase were exploration assets for $680 million and said around 60% of he overall leases were operated.
"Through this transaction we reach the necessary critical mass for our activities in the Gulf of Mexico," Eni Chief Executive Officer Paolo Scaroni said in the statement.
Eni is one of the few world oil majors which has been able to largely avoid a decline in output as it adds production both through acquisitions and as new fields come onstream.
It has made several large acquisitions recently.
Earlier this month it won with Italian utility Enel a $5.8 billion auction for assets formerly held by bankrupt oil firm YUKOS but they handed the bulk of the prize to Russian gas monopoly Gazprom.
Eni agreed to buy a package of Congolese assets from France's Maurel et Prom for $1.4 billion earlier this year and in March struck a deal to split a stake in one of those fields with Burren Energy.