An air strike by an Arab coalition battling Yemeni rebels killed 12 civilians in the northwest of the country on Wednesday, rebel media and witnesses said.

Six others were wounded in the raid that targeted a vehicle in Hiran, in Hajja province, reported the sabanews.net website that is controlled by Shiite Huthi insurgents.

Witnesses said the victims were on their way to a market.

The raid is part of increased violence in Yemen since a 48-hour ceasefire declared by the Saudi-led coalition, which is fighting the Iran-backed rebels in support of President Abedrabbo Mansour Hadi, ended on Monday.

The coalition has come under repeated criticism over civilian casualties during its operations in Yemen.

It admitted in October to killing 140 people in an air strike on a funeral in Sanaa, blaming the deaths on "incorrect information."

More than 40 people were killed in clashes Tuesday between the rebels and government forces across the country.

The Huthis overran the capital Sanaa and other parts of the impoverished country in September 2014, prompting the coalition to intervene six months later in support of Hadi.

The UN says more than 7,000 people have been killed and nearly 37,000 wounded in Yemen since March 2015.