SANAA (Reuters) - Twelve Yemeni civilians were killed by a Saudi-led air strike while riding in a pickup truck in the country's northwest early on Wednesday, residents said.

Locals said the passengers were shoppers heading to a local market in the Hiran area of northwest Hajja province, which is controlled by the Iran-aligned Houthi movement.

A Saudi-led coalition has been fighting Yemen's Houthis since March 2015 to restore the internationally recognized president, Abd-Rabbu Mansour Hadi, who lives in exile in Saudi Arabia.

A spokesman for the coalition did not immediately respond to requests for comment. But the coalition says it does not target civilians.

Thousands of air strikes have largely failed to dislodge the Houthis from the capital, Sanaa, but have hit schools, markets, hospitals and homes, killing many civilians.

Rights groups say they may amount to war crimes, but the coalition has argued that the Houthi fighters infiltrate and endanger civilian areas.

At least 10,000 people have been killed in the 20-month conflict which has unleashed a humanitarian crisis on one of the Arab world's poorest countries.

(Reporting By Mohammed Ghobari; Writing by Noah Browning)