An arrest warrant was issued for Israeli opposition leader Tzipi Livni by a London court, but was later annulled after Ms Livni cancelled her scheduled visit and did not enter Britain.

Ms Livni had been due to speak at Sunday’s JNF Vision 2010 conference in Hendon, north-west London, but cancelled over fears she would be arrested for alleged war crimes.

It is believed Westminster Magistrates’ Court issued the warrant at the request of pro-Palestinian lawyers acting on behalf of those affected by Israel’s action in Gaza during Operation Cast Lead.

It was later annulled when the magistrates were informed that Ms Livni had not come to Britain.

A spokesman for Her Majesty’s Court Service said the circumstances surrounding the issuing of the warrant are being investigated.

The British Foreign Office has said it is “looking urgently” at the implications of the case. Last year Foreign Secretary David Miliband had indicated the government would close the loophole in legislation allowing private individuals to seek the arrest of those suspected of war crimes under “universal jurisdiction”. That move was scrapped due to the anti-Israel mood in Britain following Cast Lead.

The issuing of the warrant will place further strain on Anglo-Israeli relations, with the Israeli Foreign Ministry calling the situation “absurd” and warning that relations would suffer if the British government does not “immediately amend the law”.

In September, the same magistrates’ court rejected requests for an arrest warrant for Defence Minister Ehud Barak, who had attended the Labour Party conference in Brighton. He had diplomatic immunity as a senior minister and official guest.