Air strikes killed five civilians and wounded at least 14, including four children, outside the northern Yemeni city of Saada on Tuesday, a Reuters witness and medics said.

A Saudi-led coalition that intervened in Yemen's war in 2015 to try to restore its president to power has conducted frequent air strikes targeting Iran-aligned Houthi rebels and has often hit civilians, although denies ever doing so intentionally.

Medics and a Reuters photographer who saw the wreckage in Saada said an initial air strike destroyed a house in the outlying Sohar district of the city, the main stronghold of the Houthis who control much of northern Yemen.

The medics said two further air strikes hit paramedics who were trying to lift the victims from the rubble.

A spokesman for the Saudi-led coalition could not immediately be reached for comment.

The coalition entered Yemen's conflict three years ago against the Houthis after they ousted the internationally recognised government of President Abd-Rabbu Mansour Hadi.

The war has killed more than 10,000 people, displaced more than 2 million and driven the country - already the poorest on the Arabian Peninsula - to the verge of widespread famine.