Britain’s largest trade union has said its vote to boycott “apartheid” Israel and recognise “state-sponsored ethnic cleansing” has nothing to do with events on the ground.

UNITE, which has over 1.4 million members, also voted against a motion aimed at “building bridges” between Palestinian and Israeli organisations at its annual conference in Liverpool.

By a show of hands, delegates voted to pass a motion “noting that Israel continues to govern as an apartheid state and is guilty of the crime of apartheid”.

The wording further states that “the oppression faced by ordinary Palestinians at the hands of their colonial oppressors and the way in which their plight is used as a political bargaining chip cannot be allowed to continue”.

Referring to Jewish settlements as “colonies,” it also states that Israel had “a deliberate policy to criminalise and intimidate the general Palestinian population”.

Delegates voted to “develop a strategy around BDS within the next 12 months, notably against complicit companies involved in the occupation, the apartheid wall and the illegal settlements, such as Veolia, G4S and Sainsbury’s”.

Leverage would be applied “through workforce pressure, contracts and pension funds,” it said, and the union would “encourage members to call on supermarkets and retailers to stop using companies which export goods from illegal settlements”.

The result was condemned by Jewish communal groups, with a spokesperson for the Fair Play campaign saying: “Instead of peace, dialogue and progress, UNITE has once again chosen the politics of division, discrimination and boycott, divorcing itself from the hopes and aspirations of ordinary Israelis and Palestinians.”

However, the vote was welcomed by Mohammad Taj, president of the Trade Unions Congress (TUC), with Jim Kelly, chair of the union’s London and Eastern Region, appearing to link the vote to the ongoing conflict in Israel.

“The first thing we need to do, following the resolutions just passed, is to respond and condemn [Israeli Prime Minister Benjamin] Netanyahu’s cynical exploitation of the deaths of the three teenagers to push his agenda of ethnic cleansing of Gaza and the West Bank,” Kelly said.

“The trade union movement must raise its voice in opposition to these murderous military attacks on the Palestinians and the campaign of collective punishment.”

UNITE’s director of communications, Pauline Doyle, later strenuously denied that the vote was linked to events in Israel, saying: “The deadline was for the submission [of motions] was April… It was a coincidence that the debate was held with the tragic killings of the Jewish and Palestinian boys as the backdrop.”

She added: “There is nothing to read into it other than it was our third policy conference which is held every two years. Branches submitted motions on a variety of issues and this was one.”

UNITE has consistently supported for a two-state solution but which has never before signed up to the Boycott, Divestment and Sanctions (BDS) campaign.

As such, the vote marks a significant departure for the union only days after revealing that it will help fund the 2015 election campaign of Labour leader Ed Miliband, to whom the vote will come as an embarrassment.

On Monday, a spokesman was at odds to stress that Miliband’s opposition to boycotts remained unchanged, saying: “He made both his and the Labour Party’s position on this clear at a recent Labour Friends of Israel event…That was his firm position then, and remains his firm position now.”