Michel Massih, the UK-based lawyer taking the case to court, said that he believed that the British government was obliged "to actively pursue people who are alleged to be involved in war crimes".
"One does not need, at this stage, to provide more than a basic prima face case and the suggestion would be that Barak certainly was in a position where he has to answer some of the allegations made about the commission of crimes by Israeli troops," he told Al Jazeera from London.
Some 1,400 Palestinians, at least one-third of them women and children, were killed in Israel's December-January offensive in the Gaza Strip.
"If the Israeli courts were themselves to investigate there would be no need to have recourse to international tribunals"
Israel said the air, naval and ground assault on the territory was aimed at halting rocket attacks by Palestinian fighters.
Massih said that the case would be based on a number of sources of evidence, including reports by Amnesty International and other human rights organisations and the UN investigation into the war.
After the UN human rights commission report, complied by Richard Goldstone, a South African prosecutor, was published, Barak condemned its findings as political and faulted its methodology.
"Although I am incensed by the Goldstone Report, I must admit that I was not surprised," he wrote in The Wall Street Journal. "It is, more than anything else, a political statement - not a legal analysis."
'Punished and terrorised'
Goldstone's report said that the Israeli offensive had "punished and terrorised" Palestinian civilians as troops had failed to take precautions to minimise civilian casualties and in some cases had deliberately attacked them.
|Around 1,400 Palestinians were killed as Israel pounded the Gaza Strip [EPA]
The report also accused Palestinian fighters of committing war crimes and possible crimes against humanity as they fired rockets into southern Israel.
"If the Israeli courts were themselves to investigate, there would be no need to have recourse to international tribunals," Massih told Al Jazeera.
"There are allegations of war crimes, there are families seeking redress and because these families are seeking redress they have asked the advice of lawyers in Palestine who have asked the advice of lawyers in the United Kingdom."
In 2005, human rights groups criticised 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 and was allowed to return to Israel.