Three children were killed and three more critically wounded by rebel mortar fire in a neighbourhood of Yemen's third city Taez, the official Saba news agency said Saturday.

"The Iranian-backed Huthi militia targeted the Al-Kamp neighbourhood with... shells, which led to the death of three children," Saba said.

Among the three wounded children, one has had his legs amputated and "all of them are in a critical condition", it added.

A doctor at Taez hospital confirmed the report to AFP, and said the toll could rise.

Taez is a city of 600,000 people under government control in the southwest of Yemen, a country that has been at war for the last seven years.

A Saudi-led military coalition supports an internationally recognised government against the Iran-backed Huthi rebels.

Thousands of people have been killed by the conflict and millions displaced.

In recent weeks, fighting has intensified around the government's sole remaining northern stronghold -- the city of Marib in oil-rich Marib province.