A series of labour disputes at key ports worldwide is threatening to increase congestion in a booming boxship market.

Charter and box rates are already at record highs for some vessel sizes as demand surges amid an imbalance of empty boxes between Asia and the West and delays from the 20,388-teu Ever Given (built 2008) grounding in the Suez Canal.

Truckers at Los Angeles and Long Beach in California walked out on Monday in a row over alleged labour law violations by Universal Logistics Holdings-affiliated companies.