In the heaviest raids yet of the six-day Saudi-led air war against Shiite Huthi rebels, explosions lit up the skies over Sanaa on Monday night and rocked other parts of the country on Tuesday.

Amnesty International accused the Saudi-led coalition of "turning a blind eye to civilian deaths" as it reported four children were among six burned to death in strikes on Ibb, in central Yemen.

But the spokesman for the Saudi-led coalition said it does not intend to kill civilians even though the Huthis had moved fighters into villages.