Yemeni security officials say pro-government forces backed by Saudi-led airstrikes took an island in the Red Sea from Shia rebels, just hours before a weeklong ceasefire went into effect.
Tuesday's seizure of Zuqar island also comes as delegations from Yemen's warring factions convened for peace talks in northern Switzerland.
Yemeni officials said fighting intensified across the country as both sides sought to consolidate positions ahead of the U.N.-brokered meeting. The officials spoke on condition of anonymity in line with regulations.
Past efforts to end the conflict between the internationally recognized government and the rebels, known as Houthis, have failed.
The two sides initially agreed to halt fire at midnight Monday but the coalition delayed the truce to midday Tuesday. There was no immediate word if the ceasefire was holding.