Manchester-based IT security firm NCC Group has completed its fourth acquisition in under two years with a £14.4m swoop to expand its presence in the United States - and has secured further funding to continue its buying spree.

NCC has bought iSEC Partners, an IT security testing services provider based in San Francisco. The deal takes NCC Group's spending on takeovers to over £40m since November 2008. In that time it has acquired three other UK businesses, including Wilmslow's SDLC Solutions and Meridian Services International, which is based in Warrington.

NCC will pay £8.1m initially for iSEC, with further sums due over the next three years if performance targets are met. In a stock market statement, NCC said iSEC made pre-tax profits of £1.5m on revenues of £4.9m in the year to July, and had an order book of £2m.

The company was founded in 2004 and employs over 30 full-time staff, with offices in Seattle and New York as well as California.

It provides testing to secure networks, applications, websites and databases against security threats. Customers include blue-chip organisations and international financial institutions.

NCC chief executive Rob Cotton said the deal was a 'key strategic development' for the group as it substantially increases its presence and profile in the US, widens its capabilities and brings a number of blue-chip customers.

"Furthermore, the acquisition will enable us to provide our UK customers with US security testing services while iSEC Partners' customers will now have access to our European capabilities," he said.

The deal is NCC's fourth in the field of network testing and software security, but its first in the US, where Mr Cotton said in July he was looking for further expansion.

NCC also announced its has increased its revolving bank credit facility from £25m to £35m in consideration of further acquisition opportunities. Shares in NCC Group, which is based on Oxford Road, ticked up 0.5p to 428.25p, valuing the business at more than £148m.

Stuart Moss of Rickitt Mitchell advised NCC Group on the acqusition of iSEC Partners.