More than two thirds of FTSE 100 firms use social networking site Twitter but have yet to maximise its potential to promote their employer brand, research has shown.

The same number, 67, of FTSE 100 businesses also preferred Twitter to Facebook for engaging with staff, customers and future recruits, according to the study by Threepipe Communication PR agency.

Analysis of the Twitter activity of the UK’s leading blue-chip firms showed that 63 out of the 100 were actively tweeting, while only 33 have a Facebook page.

But only six organisations use either of these social media networks to raise brand awareness around their corporate and social responsibility work, and only 11 promote the social channels for customer services or as a helpline.

Firms in the banking, retail and insurance sectors were most engaged with online networks, with top tweeters including Barclays, Marks and Spencer and Aviva.

Meanwhile, fashion brand Burberry was the most popular FTSE 100 company on Facebook with more than four million friends.

Barclays is mentioned on Facebook every three minutes, mainly because it sponsors the Premier League, while Next has the most passionate and engaged social media community with 43 per cent of customers repeatedly mentioning the retailer on these sites.

But despite the potential for brand promotion, only five companies, Barclays, Lloyds Banking Group, Pearson, Reckitt Benckiser and WPP, have a dedicated social media page on their corporate websites.

Researchers said that the manufacturing, mining and real estate sectors were “practically invisible” in social media terms, with one exception being mining giant Rio Tinto which was named as a top Twitter user, tweeting its annual results in the past year.

Beth Carroll, head of the social media division Three_D at the PR agency, said: “It’s interesting to see that companies favour Twitter over Facebook, given the latter is much bigger on a global scale.

“Overall, the research suggests that a majority of FTSE firms recognise the importance of engaging their stakeholders in a dialogue via mediums such as Twitter, and responding to their comments directly.”