Siri has interrupted a White House press conference to try – and fail – to answer a question on the Iran nuclear deal.

Press secretary Josh Earnest was being grilled about Barack Obama’s failure to gain Republican support when the voice command service made its timely intervention.

As a journalist asked if the President was “upset” that he could not get even one member of the opposition on board, the distinctive female voice calmly intoned: “Sorry, I’m not sure what you want me to change.”

As the assembled journalists burst into laughter, Mr Earnest even cracked a smile on the podium.

“That was on time,” a woman could be heard remarking in the background in footage broadcast by Fox News.

Reporters joked that it was unclear whether the gadget was speaking on behalf of the White House.

“Does Siri make it into the transcript?” wondered Potus Channel correspondent Jared Rizzi, on Twitter.

Siri is Apple’s voice command service on iPhones, iPads and its other devices that lets people send messages, make phone calls and perform other functions, as well as being able to converse.