Yemeni security officials in the western city of Taiz say Shiite rebels have captured two neighborhoods in heavy fighting with government troops.

The officials, who are neutral in a conflict that has split Yemen's security forces, said Tuesday that 40 Shiite rebels and 15 pro-government fighters have been killed in the last 24 hours in Taiz, Yemen's third largest city. They say shelling by the rebels, known as Houthis, has killed three civilians.

The officials say Houthis seized the Jabal al-Waash and the Madinat al-Saleh areas, both on the city's western outskirts. They spoke on condition of anonymity because they are not authorized to brief reporters.

The U.N. says the conflict in Yemen has killed more than 2,100 civilians.