The Barcelona port stevedores' union has refused to load and unload any military material headed to Israel amid the war in Gaza, where Israel ruthlessly carried out a military campaign, killing over 10,300 Palestinians - mostly children and women - since 7 October.
The union also urged the protection of civilian populations in areas of conflict, following a similar move by Belgian transport unions last week.
In a statement, the workers stressed the "absolute rejection of any form of violence" and see it as an "obligation and commitment to vehemently defend" the Universal Declaration of Human Rights, which they say are being violated in Gaza, and other war-hit areas.
The decision on Monday is mostly symbolic and seeks to encourage other Spanish ports to follow suit, the secretary of the OEPB union, Josep Maria Deop, told Reuters on Tuesday.
The OEPB is the only union representing the 1,200 stevedores at Barcelona's port.
The union said it would work with local NGOs to detect which ships were carrying weapons headed to Israel, the Spanish website El Diario said. Deop stated he was convinced there were military shipments from Barcelona because "it's a port that moves all types of goods".
The union also carried out a similar move in 2011, in an effort to hinder weapons shipment to Libya during the NATO military intervention.
Barcelona's port authority declined to comment and said it did not have data on military shipments, Reuters said.
Israel launched a brutal onslaught on the Gaza Strip on 7 October, killing at least 10,328 Palestinians, including 4,327 children.
Tel Aviv has used advanced weaponry to carry out its atrocities and received military supplies and aid from its ally, the US.
Hospitals, places of worship and residential buildings have been struck, leaving Gazans with few options as they seek refuge from Israeli shelling.
Spain exported military equipment worth 1.3 billion euros ($1.39 billion) in the first half of 2022, with shipments to Israel amounting to 9 million euros, according to the latest available official data.
Spanish officials have stated that Madrid does not plan to export any lethal military equipment to be used in Israel's war in Gaza, state news agency EFE cited government sources as saying last week.
The OEPB said it opposed all types of violence wherever it happens, including the occupied and war-hit Palestinian territories, and that its boycott seeks to protect civilians anywhere.
"No cause justifies sacrificing civilians," it said.
Barcelona's move came as similar actions were taken by ports elsewhere. Last week, five Belgian transport unions - ACV Puls, BTB, BGTK, and ACV - Transcom - refused to handle weapons headed to Israel.
The unions said in a joint statement that they were demanding an immediate ceasefire in Gaza, where the humanitarian situation is rapidly worsening.
On Monday, pro-Palestine demonstrators blocked traffic near the port of Tacoma, Washington state, where a military supply ship bound for Israel had arrived.
(Reuters and °®Âþµº Staff)