The information and communication technology (ICT) sector has resisted the economic crisis and is becoming a key infrastructure for the world's economy, the OECD said Thursday.

"The expansion of mobile Internet connectivity has helped buoy the ICT sector, and in many ways the economy as a whole, during a period of sustained economic malaise," the Organisation for Economic Cooperation and Development said in a report based on a study of 250 top ICT firms.

"The Internet is becoming a key economic infrastructure, revolutionising businesses and serving as a platform for innovation," the Paris-based organisation of 34 leading industrialised countries.

The top firms registered an average annual growth rate in revenue of six percent between 2000 and 2011, with total revenue at more than $4.6 trillion (3.5 trillion euros) in 2011, or an increase of five percent over the previous year.

A key source of the growth has been an expansion of mobile connections, which overtook the number of fixed broadband subscriptions in 2009. In 2011, the estimated number of mobile subscriptions among OECD countries was at 667 million, or more than double that of the 315 million fixed connections.

"The number of mobile phone subscriptions worldwide has more than doubled since 2005 and tripled in non-OECD countries," the OECD said.

The organisation added that the top firms increased their hiring by six percent from 2010 to 2011 to take on more than 14 million people worldwide that year.

The ICT sector also "continues to attract venture capitalists, accounting for more than 50 percent of all venture capital in the United States, the world's largest market, in 2011," the OECD said.

The US and Japan accounted for the largest number of the top 250 ICT firms in 2011, while in Europe, the countries most likely to host the firms were France, Germany, the Netherlands and Britain.