The Saudi-led coalition bombarded Yemen's Hodeida overnight, taking out a telecommunications hub and triggering a nationwide internet blackout, a web monitor and AFP correspondents said on Friday.
The pro-government coalition fighting the Iran-backed Huthi rebels said they targeted a "hub for piracy and organised crime" in the city, whose port is a lifeline for the embattled country.
Global internet watchdog NetBlocks reported a "nation-scale collapse of internet connectivity" after the bombardment. AFP correspondents in Hodeida and Sanaa confirmed the outage.
Saudi Arabia's state news agency said the coalition carried out "precision air strikes... to destroy the capabilities of the Huthi militia in Hodeidah".
The Huthis said people had been killed in the raid, but the statement could not immediately be confirmed. An AFP correspondent in Hodeida described a large-scale attack.
The attack comes after the Huthi rebels hijacked a United Arab Emirates-flagged ship in the Red Sea, prompting a warning from the coalition that it would bomb rebel-held ports.
On Monday, the rebels claimed a drone-and-missile attack that struck oil facilities and the airport in the UAE capital Abu Dhabi, killing three people and wounding six others.