Guardian/ICM survey, which also found greater opposition to Israel than Palestinians, appears to find support for Lady Warsi who resigned over the issue

A majority of British voters believe Israel acted in a disproportionate manner during the recent Gaza conflict, according to the latest Guardian/ICM poll, which lends support to the arguments that persuaded Lady Warsi to resign from the government.

Amid hopes that the month-long conflict between Israel and Hamas could be ending as a ceasefire continued to hold, the poll also found greater opposition to Israel than to the Palestinians.

The poll found that 52% of voters believe Israel acted disproportionately when it responded to the firing of rockets by Hamas by launching air strikes against the Gaza Strip. It found that 19% thought Israel had acted proportionately while 29% of those polled did not know.

The findings will lend weight to the argument of Lady Warsi, who resigned last week as a senior Foreign Office minister after criticising David Cameron for his "morally indefensible" failure to describe the Israeli action as disproportionate.

More than 1,900 Palestinians, most of whom were civilians, have died in the conflict in which 64 Israeli soldiers have also been killed. Three civilians have been killed in Israel – two Israelis and a Thai agricultural worker.

Nick Clegg endorsed some of Warsi's criticisms as he called for the suspension of arms export licences to Israel after he also described Tel Aviv's military response as disproportionate.

The poll found that the conflict has hardened opinions against Israel, though the findings suggest there is unease about the actions of Hamas. According to the poll, 41% of voters say their opinion of Israel has worsened during the recent conflict. A larger number of voters (48%) say their opinion of Israel has remained the same. A fraction of voters (2%) say their opinion of Israel has improved while 8% say they do not know.

A fifth of voters (21%) say their opinion of the Palestinians has worsened while just 9% say their opinion has improved despite widespread international condemnation of the Israeli actions and support for the plight of Palestinian civilians killed in the Israeli air raids. A clear majority of voters (60%) say their opinion of the Palestinians has not changed while 9% do not know.

The poll asked voters about their views on "the Palestinians" – not distinguishing between Hamas, which controls the Gaza Strip, and the Fatah faction of the Palestinian president Mahmoud Abbas, which controls the West Bank. A unity government was agreed in June. Hamas is condemned by Tel Aviv and the US as a terrorist group bent on the destruction of Israel.

The belief among a majority of voters that Israel acted in a disproportionate manner is likely to be highlighted by critics of Cameron, who believe the prime minister was wrong to prevent Tory ministers from using such language. In his letter to Warsi after her resignation, the prime minister described the situation in Gaza as "intolerable" as he raised concerns about "the heavy toll of civilian casualties". But he said Israel had the right to defend itself. Hamas is estimated to have launched 3,000 rockets from Gaza in recent weeks.

ICM Research interviewed a random sample of 1,002 adults aged 18+ on 8-10 August 2014. Interviews were conducted across the country and the results have been weighted to the profile of all adults. ICM is a member of the British Polling Council and abides by its rules.