Members of the International Longshore and Warehouse Union Canada (ILWU Canada) voted 99.24% in favour of strike action against member companies of BC Maritime Employers Association (BCMEA) “if necessary”.

The BCMEA represents 49 member companies at Canadian West Coast ports which include the key gateways of Vancouver and Port Rupert.

Related: Port of Seattle shuts down on Saturday as ILWU and PMA war of words ramps up

Talks between ILWU Canada and BCMEA for a new labour contract began in February this year and negotiations under the Federal Maritime Conciliation Service started on 28 March ending without agreement of 30 May. The strike vote by ILWU Canada was taken during a 21-day cooling off period, meaning the earliest strike action could take place is 24 June following a three-day notice period.

Strike action would include the Port of Vancouver, Canada’s largest port that handled 4m teu of container traffic in 2022, as well as 99m tonnes of bulk cargo, and 20m tonnes of breakbulk.

Related: Dockworkers disrupt US West Coast ports as contract talks drag on

The vote in favour of strike action at Canadian West Coast ports comes at time when US West Coast labour contract talks have become increasingly fraught with the ILWU taking work slowdown actions at a number of key ports.

The Pacific Maritime Association (PMA), which represents US West Coast terminal operators and carriers said on Monday said that the ILWU had resumed the practice of withholding lashers from terminals in Los Angeles and Long Beach ports causing vessels to miss scheduled departures.

At the weekend the Port of Seattle was shut down following labour actions.

“At the Port of Seattle, ILWU continued to stage disruptive work actions that led to containerized terminal operations coming to a halt. In some cases, the Union slowed down operations, resulting in longshore workers being sent home,” the PMA said.

The ILWU has denied that its actions were leading to the closure of US West Coast ports and that its members continued to work under an expired collective bargaining agreement.

In a growing war of words between the two sides the PMA retorted on Monday, “For months, the ILWU has staged disruptive work actions targeting the West Coast’s largest ports. These actions have either slowed operations or shut them down altogether, impeding the supply chain and leaving ships and the American exports they carry sitting idle at the docks.”

The previous contract between longshoremen and US West Coast ports expired on 1 July 2022, and negotiations on a potential new deal have dragged on since 10 May 2022 with few signs of progress.