The Saudi-led coalition said pro-government forces in Yemen launched a new offensive on Monday night against the rebel-held port city of Hodeida, after an 11-week pause during UN efforts to hold peace talks.
"A military operation to liberate Hodeida and its port has begun on multiple fronts," a senior coalition official told AFP, speaking on condition of anonymity.
Brigadier General Ali al-Taniji, the commander of coalition forces on Yemen's west coast, confirmed the operation in remarks to state media in the United Arab Emirates, Saudi Arabia's main partner in the coalition.
Pro-government forces launched air raids against rebel positions in and around the city of 600,000. Residents told AFP they had heard explosions.
The coalition accuses the Tehran-aligned Huthi rebels of smuggling arms from Iran through Hodeida and has imposed a partial blockade on the port, which the rebels seized in 2014.
In June, it launched a major operation to retake both the city and its port, the entry point of most of the impoverished country's imports and aid.
The troops, backed by coalition air strikes, have retaken a number of towns across Hodeida province but have not yet breached the city.
The coalition in July announced a temporary ceasefire in Hodeida to give a chance to UN-brokered peace talks.
The UN's Yemen envoy, Martin Griffiths, arrived Sunday in the rebel-held capital Sanaa.
He is pushing for new negotiations after a failed attempt to bring the two sides together in Geneva earlier this month.
Saudi Arabia and its allies intervened in 2015 in the conflict between embattled Yemeni President Abedrabbo Mansour Hadi, whose government is recognised by the United Nations, and the Huthis.
Nearly 10,000 people have since been killed and the country now stands on the brink of famine.