Iraq’s most senior Sunni politician on Monday launched a bitter personal attack on the country’s prime minister, warning Nouri al-Maliki that the Iraqi government had only limited time to break with sectarian groups and start delivering to ordinary citizens.

In comments to the media in London, where he also met top British officials, Tariq al-Hashimi, Iraq’s vice president, said Mr Maliki had failed to break his ties with Shia militias and that Washington would only give him a limited time to succeed.