The Foreign Office has appointed a UN diplomat as the UK's special representative on the Middle East.
Mr Williams was previously a UN special envoy
Michael Williams was the UN secretary general's special co-ordinator for the Middle East peace process.
In his new role, from September he will report to the Foreign Secretary and the prime minister.
Mr Williams replaces Lord Levy, Middle East representative for Tony Blair - who himself became a Middle East envoy for the UN, EU, Russia and the US.
Mr Blair was appointed by the so-called Quartet after he resigned as prime minister in June.
Mr Williams will deal with the wider Middle East, including Iraq and Iran.
His career history includes a stint with the UN in Cambodia, the former Yugoslavia, Geneva and New York.
Between 2000 and 2005, he was a special adviser to two foreign secretaries, Robin Cook and Jack Straw.
From July 2005 he was director of Asia in the UN's department of political affairs in New York, before becoming assistant secretary general and special adviser on the Middle East to then-UN secretary general Kofi Annan a year later.
He was also involved in the implementation of Security Council Resolution 1701 which ended the Israel-Lebanon war last year.