US embassy in Australia apologises for Cookie Monster cat email

The US embassy in Australia has apologised for an email invitation featuring a cat dressed in pyjamas that was mistakenly sent out by the US state department.

The email, titled "meeting", went to an unknown number of recipients, US officials in Canberra confirmed.

It was accompanied by a photo of a cat wearing a Cookie Monster outfit and holding a plate of biscuits.

In a light-hearted apology, the embassy called the email a "training error".

"Sorry to disappoint those of you who were hoping to attend this 'cat pyjama-jam' party, but such an event falls well outside our area of expertise," US mission to Australia spokesman Gavin Sundwall told the Australian Associated Press.

"It was a training error made by one of our new staff testing out our email newsletter platform."

The US embassy in New Zealand, however, didn't miss a chance to weigh in.

Along with the words "cat pyjama-jam", the email also included words in Latin, and recipients were given an option to reply to the invitation.

Mr Sundwall said new controls would be implemented so something similar did not happen again.

The US has been without an ambassador to Australia for two years - the longest gap since World War Two.