Habitat has apologised after it assigned hashtags to its marketing tweets on Twitter that were unrelated to the content of their posts to drive traffic.

The furniture retailers inserted hashtags linked to popular topics, such as the turmoil in Iran and the iPhone, into tweets advertising its products and various special offers and discounts.

This meant that Twitter users searching for these hashtags would likely have seen Habitat's unrelated tweets.

In a statement, Habitat said: "This was absolutely not authorised by Habitat.

"We were shocked when we discovered what happened and are very sorry for the offence that has been caused."

According to Alex Burmaster of Nielsen Online, Habitat's situation shows why social media marketing must be approached in a careful manner by companies.

He told the BBC that placing advertising content on social media sites is like "gatecrashing a party".

Meanwhile, Habitat has dropped a marketing intern following the exposure of its activities on Twitter, according to a comment left by the company's press office on a story on socialmediatoday.com.

The firm said that an agency had not been responsible for the incident, blaming an "overenthusiastic" intern for the issue who no longer works for Habitat.