Saudi Arabia and Yemen's Houthi rebels have traded fresh attacks, underscoring a sharp escalation in the conflict.

Houthi authorities say Saudi airstrikes on the Yemeni capital, Sanaa, and Hodeida province killed at least 14 people and damaged a cement factory, homes and vehicles. The Houthis say they responded with attacks targeting Saudi oil facilities and airports.

The exchange comes as Saudi Arabia partially reopens Riyadh's main international airport after earlier Houthi strikes and following the collapse of a fragile ceasefire in July.