Aden (AFP) - Warplanes from the Saudi-led coalition hit Saturday two small boats allegedly carrying weapons to Iran-backed Huthi rebels on the southern coast of Yemen, a military official said.

Weapons were being unloaded from the two fishing boats near Belhaf, in Shabwa province, when the pre-dawn raid struck killing three smugglers, the military official said requesting anonymity.

The coalition has imposed a blockade on Yemen to prevent weapons from reaching the Huthi rebels and allied renegade troops loyal to ousted president Ali Abdullah Saleh.

Troops loyal to President Abedrabbo Mansour Hadi, backed by coalition air and ground support, in July pushed the rebels out of Aden -- Yemen's second city -- and four other southern provinces, including Shabwa.

But the area around Belhaf is controlled by tribesmen and some are involved in smuggling weapons to the rebels further north, the official said.

Government forces backed by the coalition launched an all-out offensive last week to push the rebels out of the southwestern province of Taez and break the siege of loyalists in its provincial capital.

The United Nations says more than 5,700 people have been killed in Yemen since the Saudi-led intervention began in March, nearly half of them civilians.