Saudi-led air strikes on Yemen's Red Sea coast have killed at least 29 rebels over the past 24 hours, military sources said on Friday.

The strikes hit two military camps, an ammunition depot and an arms transporter in Hodeida province, the sources said. Around 20 fighters and renegade troops were also wounded.

The Saudi-led coalition intervened in Yemen in March 2015 in support of beleaguered President Abedrabbo Mansour Hadi.

Read more: US cancels weapons transfers to Saudi over Yemen campaign

But despite its massively superior firepower, the rebels and their allies still control the capital Sanaa, and much of the central and northern highlands as well as the Red Sea coast.

Pro-government forces launched a major offensive earlier this month aimed at ousting the rebels from Dhubab district at the southern end of the 450 kilometre-long coastline.

Amnesty International and Human Rights Watch have called on Washington, London and Paris to stop their deliveries of bombs and other weapons to Riyadh because of concerns over civilian casualties.

More than 7,000 people have been killed in the conflict, mostly civilians, according to the United Nations.