Dock workers in Liverpool voted to strike over pay, threatening to disrupt UK trade and adding to a summer of labor unrest brought on by spiraling inflation.

More than 500 employees backed a stoppage after being offered a 7% pay increase by Peel Ports Ltd. that the Unite union said was “inadequate,” according to a statement from the labor group Monday. The ballot had an 88% turnout with 99% of workers voting in favor of strikes, Unite said. 

The Port of Liverpool is Britain’s fourth-largest and a key hub for trans-Atlantic imports and exports. Stoppages will add to supply-chain disruption expected from an eight-day action planned later this month at Felixstowe, the UK’s No. 1 container terminal. Strike dates for Liverpool haven’t yet been set.

Maintenance engineers at Liverpool’s port could also strike over pay, Unite said. Over 60 engineering staff are being balloted on halting work, with the vote closing on Aug. 24, the union said. 

The rising cost of living is prompting dockers to seek better deals from port operators. Unite, which represents over 1,900 workers at Felixstowe, previously turned down a 7% pay offer along with a £500 bonus offered by that port’s owner CK Hutchison Holdings Ltd.