SANAA - Strikes by Saudi-led coalition aircraft killed at least 54 people in attacks across Yemen on Tuesday, including four children, the Houthi-run Sabanews.net news agency and residents said.

Residents said the air strikes targeted two houses in Ans in Dhamar province, one of which belonged to a supporter of the Houthi group which the Saudi-led coalition is trying to dislodge from Yemen.

Sabanews.net said 13 other civilians were killed in air strikes in the northern Saada province, a stronghold of the Houthi group which hails from the Zaydi branch.

Air strikes also killed 13 people in attacks on roads and bridges in al-Mahawit province, northeast of the capital Sanaa, and 10 more in the nearby Hajja province, Sabanews.net said.

The reports could not immediately be verified independently.

The Saudi-led coalition began air strikes against the Houthis and their allies, forces loyal to former president Ali Abdullah Saleh, in late March after they pushed from their northern stronghold towards the southern port of Aden. International human rights groups have expressed concern at the number of civilians killed in the raids.

The coalition, which says the Houthis are allied with Iran, has stepped up air strikes on Sanaa and other Houthi-held areas since a Houthi missile killed more than 60 Gulf Arab troops stationed in Marib province on Sept. 4.

On Sunday, five Saudi soldiers were killed near the border with Yemen, while a Saudi-led military coalition began an offensive to drive Houthi militia forces out of Marib. The Houthis seized Sanaa last September and eventually forced President Abd-Rabbu Mansour Hadi and his administration to flee to Saudi Arabia.

Meanwhile, Yemeni loyalist forces, backed by the Saudi-led Arab coalition, said they were advancing Tuesday in a key province east of Sanaa, on the third day of a major offensive against rebels.

The coalition intensified its air strikes against the Iran-backed Huthi rebels earlier this month after a missile attack killed 60 Gulf troops, most of them Emiratis, in Marib province.

Troops loyal to exiled President Abedrabbo Mansour Hadi on Sunday began an all-out offensive against the rebels in Marib, aiming to retake the capital a year after it fell to the insurgents.

Supported by coalition air cover and ground forces, pro-Hadi fighters captured two strategic hills in the rebel stronghold of Sirwah, on the route to Sanaa, an officer said.

“We have pushed the Huthis out of these two hills and entered Al-Zor,” a rebel position near Sirwah, Captain Zaid al-Qaisi of the Marib-based 14th Brigade told AFP.

“Coalition ground forces, mainly from the United Arab Emirates and also Saudi Arabia, are participating in the offensive,” he said, adding that they have been clearing mines planted by the rebels.

The UAE had said its troops were taking part in the latest operations in Marib and announced Monday the death of a second soldier.

Clashes also raged southwest of the Marib provincial capital, close to the historic site of the Marib Dam, military sources said.

Marib city is controlled by troops and tribes loyal to Hadi, but parts of the oil-rich province are still in the hands of the rebels.