Including the debt, New York-based KKR will pay £1.4 billion for the business.

KKR said it would pay 95 pence per Northgate share, a 49% premium to the stock's Thursday close and 60% above the closing price on Dec. 11, the day before Northgate confirmed it was in takeover talks. The Northgate board is recommending shareholders accept KKR's offer.

"Kohlberg Kravis Roberts is offering a price which reflects Northgate's fundamental value, and under Kohlberg Kravis Roberts' ownership, Northgate and all its stakeholders can look to the future with confidence," Northgate chairman Ron Mackintosh said in a statement.

Northgate's stock has bounced around during the past month, first dipping below 60 pence on analyst concerns about its £790 million debt burden and then jumping above 70 pence when the group said it had become the target of an approach. The company has always downplayed the debt fears and noted in press reports Friday that KKR planned to add leverage.

Northgate's shares surged 44%, or 28.25 pence, to trade at 92 pence by late Friday afternoon in London.

Hemel Hempstead, England-based Northgate specializes in human resources and public safety services software as well as managing IT and telecommunications infrastructure for corporations. It operates in 46 countries and in May agreed to pay €377.9 million for Belgium's Arinso International NV. Northgate said KKR first approached it in November.

In the six months ended Oct. 31, Northgate posted sales of £246.3 million, a 49% increase over the same period a year earlier, and earned an operating profit of £31.5 million in operating profit, a 23% gain over the past year's period.

The company employs nearly 6,500.

Private equity firms Warburg Pincus and General Atlantic LLC own 13% of Northgate.

KKR has been an active technology dealmaker. Earlier this year, it picked up 5% of computer company Sun Microsystems Inc. through a purchase of $700 million worth of convertible bonds. Last month an investment joint venture between KKR and Palo Alto, Calif., peer Accel Partners sold its controlling stake in public sector software specialist Saber Holdings Inc. to EDS Corp. for $420 million.

Goldman, Sachs & Co.'s Mark Sorrell, Nicholas van den Arend, Nimeah Khiroya and Phil Raper were financial advisers to KKR.

Northgate took financial advice from Citigroup Inc.'s Mark Fisher and Andrew Chapman; Hoare Govett Ltd.; and Rothschild's Dominic Hollamby, Warner Mandel and Jeremy Millard.