Senior official describes shadow chancellor as a 'nightmare' in email mistakenly sent to Tory MP instead of Labour pollster

Labour is blaming a "fat-finger trade" error for the leaking of an email trail in which a senior official in Ed Miliband's office described the shadow chancellor, Ed Balls, as a "nightmare".

Torsten Henricson-Bell, a former adviser to Alistair Darling who is now Miliband's chief economic adviser, mistakenly sent the emails to the Conservative MP for Halesowen & Rowley Regis, James Morris, rather than to the Labour pollster of the same name.

The emails, which were sent last Wednesday, were published in the Mail on Sunday under the headline: "Nightmare! He refuses to obey orders."

The exchanges revolved around Labour's response to an upbeat economic forecast by Mark Carney, the governor of the Bank of England, on the day of the publication of the bank's inflation report.

Alex Belardinelli, the shadow chancellor's main media adviser, asked for approval of a response by Balls. It said: "Could we get this out pls? cleared at this end [by Balls] and essentially the same script as we had on GDP day the other week. Thanks."

The Balls response began, according to the Mail on Sunday, with the words: "After three damaging years of flatlining …". It then warned about the "cost of living crisis", called for a "recovery that's built to last" and an "economy that works for working people".

Henricson-Bell forwarded the email to Greg Beales, Miliband's head of strategy, with a message at the top. It said: "As an example of why we're having problems on EB messaging – this is his current three-part argument: Cost of living; Recovery built to last; Economy works for working people. Nightmare."

Beales replied to Henricson-Bell saying: "When did built to last become a part of our thing?"

The emails highlighted an open secret at Westminster: there is little love lost between the Miliband and Balls teams.

But Labour sources played down the tensions and dismissed speculation that the emails were deliberately leaked from within the Labour party to cause damage.

A quick scan of Henricson-Bell's email account showed that he had mistakenly sent them to the Morris. "It was a fat-finger trade," one source said, referring to the City slang for a computer error that can cost millions of pounds. The source added that the differences were over messaging and not over substance.

A spokesman for Miliband said: "Ed Balls is entirely right. After three years of flatlining, there is no growth for the majority of families in this country. Prices are rising faster than wages. Just this week we saw figures which showed that people are on average £1,600 a year worse off since David Cameron came to power."