Tens of thousands of Yemenis gathered in several cities on Friday to hear their leaders condemn U.S. and British strikes on their country in response to attacks by Houthi militants on Red Sea shipping to protest against Israel's bombardment of Gaza.

The U.S. and Britain carried out dozens of air strikes on Houthi military targets overnight, widening a regional conflict stemming from Israel's war in Gaza.

"Your strikes on Yemen are terrorism," said Mohammed Ali al-Houthi, a member of the Houthi Supreme Political Council, referring to the United States. "The United States is the Devil."

The Iran-aligned Houthis waded into the Israel-Hamas conflict - which has spread around the Middle East since it began on Oct. 7 - by attacking vessels in vital shipping lanes and firing drones and missiles towards Israel itself.

(Additional reporting by Doina Chiacu and Ahmed Rasheed; Writing by Michael Georgy; Editing by Kevin Liffey)