The Food Standards Agency's latest satfat campaign has come under fire for wasting money after signing up fewer than 100 Twitter followers in its first 48 hours.

In a £1.65m campaign, the agency is running a four-week series of ads in The Sun promoting its 21-day Sat Fat Challenge, as well as a string of poster and radio ads. The campaign includes an iPhone app and Twitter functionality. But 48 hours after the ads first appeared in the newspaper, fewer than 100 Tweeters had signed up, and only five people had rated the app and they gave it one star, the lowest-possible rating.

"This is a ludicrously wasteful campaign quangos should not spend millions on big advertising and lobbying campaigns," said Taxpayers' Alliance chief executive Matthew Elliot. "For food businesses struggling to survive it is an insult to see the regulatory body squander so much taxpayers' money."

An FSA spokesman said more than 2,300 people had so far seen tweets relating to the campaign and it was using Twitter so users would pass on the campaign to other users.