About 30 per cent of the large organisations will continue to block employees' access to social media sites by 2014, compared to 50 per cent in 2010, according to technology research firm Gartner.

The number of organisations blocking access to all social media is dropping by around 10 per cent a year, it said in a statement.

"Even in those organisations that block all access to social media, blocks tend not to be complete," said Andrew Walls, Research Vice-President at Gartner.

"Certain departments and processes, such as marketing, require access to external social media, and employees can circumvent blocks by using personal devices such as smartphones. Organisations need to turn their attention to the impacts of social media on identity and access management (IAM)," the statement said.

The social media environments include mechanisms to collect, process, share and store a more complete range of identity data than do corporate IAM systems. They enable a more complete view of identity, one that extends beyond the bounds of organisations. For IAM managers, this is both a threat and an opportunity, it said.

Identity data and social media platforms can expose organisations and users to a wide variety of security threats, but organisations can also use this identity data to improve support for their own IAM practices and the ambitions of business stakeholders, it was noted.