"As a high contracting party to the Geneva Convention, the British government should be arresting Barak for war crimes, not treating him to dinner."
Race against time
Lawyers for the families said on Tuesday that an application had been lodged at the City of Westminster Magistrates' Court in London for an arrest warrant to
be issued for Barak.
The families have accused Barak of committing war crimes including the assassination of a senior Palestinian minister and unlawful killing of civilians during the Gaza war at the beginning of this year.
Tayab Ali, a lawyer for the group, said they were racing against time to have their case heard.
"It has got to be today otherwise we run the risk of Ehud Barak leaving the country," he said.
Barak is expected to meet Gordon Brown, the British prime minister, and David Miliband, the foreign secretary, on Wednesday.
Miliband said the meetings would go ahead regardless of the threatened court action.
"He is the democratically elected defence minister of Israel and I will be pleased to meet him," Miliband said.
More than 1,400 Palestinians, at least one-third of them women and children, were killed in Israel's December-January offensive in the Gaza Strip.
Israel said the air, naval and ground assault on the territory was aimed at halting rocket attacks by Palestinian fighters.
In 2005, human rights groups criticised the British authorities for failing to arrest Doron Almog, an Israeli army general for whom an arrest warrant for alleged war crimes had been issued, when his aircraft landed in London.
Almog stayed on the aeroplane at Heathrow airport after apparently being informed that he could face arrest. He was allowed to return to Israel.