Labour Party MPs are said to be red-faced, after discovering that prominent blogger David Farrar is not the Prime Minister of New Zealand.

Mr Farrar has been the target of numerous attacks by Labour Party MPs over the last couple of years.

A source inside Labour has confirmed that party officials identified Farrar as the leader of the country shortly after the 2008 election, despite being given evidence to the contrary. Rumours that John Key was the actual leader of the National Party as well as the Prime Minister of New Zealand were dismissed at the time as mere speculation.

But this morning, in a shock announcement, Mr Key revealed that he is in fact the Prime Minister, and that David Farrar is merely an enthusiastic National Party member with a popular blog, a couple of newspaper columns, and only moderate political influence.

Commentators have observed that Labour’s obsession with David Farrar has been a distraction that has turned off many left-leaning voters.

Labour MP Trevor Mallard admitted today that the party had made an “embarrassing but understandable error” over the identity of the Prime Minister.

However, he was unrepentant over Labour’s policy of giving free publicity to David Farrar by attacking everything the commentator writes or says.

Mr Mallard also vowed to keep piling the pressure onto Mr Farrar.

“He’s not fit to hold office. He’s certainly not fit to be in Cabinet,” said Mr Mallard.

“When Parliament reopens we’ll be piling the heat on David Farrar, and holding him to account. This Farrar-led government has been a disaster for New Zealand.”