David Cameron has been taken to task by a Labour MP who accused him of using an "unjustifiable, rude and offensive phrase" when replying to his question during PMQs.

In a reference to former Co-op bank boss Paul Flowers, the prime minister had joked Michael Meacher must have been taking "mind-altering substances" when he asked about government economic policy.

Mr Cameron said it had been "Commons banter", and he had tried to answer with a "light-hearted remark" and it was important to have a "sense of humour on all sides".

As Mr Meacher asked for an apology, the Speaker stepped in while some MPs were noisy and laughing, After the PM replied and the chamber emptied, some shouted "shame".