However, Sumitomo's decision to sell a significant chunk of its North Sea business raises questions about the Japanese giant's commitment to the area.
Ithaca has agreed the terms for a deal that will result in the second signficant increase in the company's exposure to the UK North Sea within 15 months.
The company is buying stakes in the Cook and Pierce fields east of Aberdeen and the Wytch Farm onshore field in Dorset.
The acquisitions will result in Ithaca increasing production by around 25 per cent on first quarter levels.
The deal is the latest in a series of North Sea acquisitions by independents such as Ithaca, who believe they can generate big returns from investing in assets that others may not want to spend on.
Moves by majors such as BP and Shell to focus on big fields have led to them off-loading smaller, non-core assets. Shell put its 25.77 per cent stake in the Cook field up for sale in February.
Private equity investors have also shown appetite for North Sea assets.
Les Thomas, chief executive of Ithaca, said: "The transaction is directly in line with our strategy to further diversify and expand our producing asset portfolio. Moreover, each of the assets has clearly defined upsides."
In April last year, Ithaca bought North-Sea-focused Valiant Petroleum for £203m.
Ithaca could gain tax benefits by acquiring North Sea production. Companies can set losses incurred on exploration and development work in the North Sea against revenues generated there.
Ithaca is paying $14.2 per barrel for the 12 million barrels reserves it is acquiring, but only $12 per barrel after taking account of tax losses.
It is generating significant amounts of cash from its North Sea operations that the company can use to service debt taken on to fund acquisitions or development work.
The Valiant acquisition helped Ithaca achieve a 50 per cent increase in average production, to 9,222 barrels in the first quarter from 6,148 in the same period last year.
The amount of cash it generated from operations increased to $43.7m from $34.8m.
Ithaca's share of production from the assets acquired from Sumitomo will be around 2,500 barrels per day in 2014.
The deal includes three of the four producing assets held by Sumitomo.
The company has a 2.2 per cent stake in the giant Elgin Franklin field. It also has exploration acreage, and made a find on the Avalon prospect, north east of Aberdeen, in May.
Sumitomo acquired the Elgin Franklin stake in a deal completed with a consortium to acquire the former Oranje-Nassau (UK) business for $860m in 2009. On the website of its Summit Petroleum North Sea subsidiary, Sumitomo says: "While continuing to (pursue) UK opportunities, Summit is now actively looking to expand operations into Africa margins in the near future."
The company also says: "In 2012 Summit Petroleum drilled its first well as an operator and is committed to an exploration strategy."
It adds: "Summit Petroleum is positioning itself to obtain a good balance between exploration, development and production activities."
No-one was available to comment at Sumitomo.
Ithaca is acquiring a 20 per centstake in Cook, in which it has 41.346 per cent already. It is buying a 7.48 per cent stake in Pierce and a 7.43 per cent interest in Wytch Farm.