Troops, Shiite rebels clash near contested Yemeni port city Security officials say heavy fighting has broken out between government-allied troops and Shiite rebels in and around Yemen's contested port city of Hodeida

SANAA, Yemen -- Security officials say heavy fighting has broken out between government-allied troops and Shiite rebels in and around Yemen's contested port city of Hodeida.

Thursday's fighting, which went on for about three hours, is thought to be the biggest breach yet of a fragile cease-fire in the city reached in U.N.-sponsored talks in Sweden last month.

Officials said the two sides used heavy weapons, including mortars, and were bringing in reinforcements.

They spoke on condition of anonymity because they were not authorized to brief the media.

The fighting took place one day after U.N. Envoy Martin Griffiths left Yemen after a two-day visit in while he sought to try and salvage the Jodeida truce, which includes the withdrawal of forces from the Red Sea port city.