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Ambulances wait on site following airstrikes on a prison in central Dhamar province, Yemen, Sept. 1, 2019. At least 50 prisoners of war were killed when the Saudi-led coalition launched a series of airstrikes overnight on a prison in Yemen's central province of Dhamar, the Houthi-controlled health ministry said in a statement early Sunday morning. (Photo by Mohammed Mohammed/Xinhua)

SANAA, Sept. 1 (Xinhua) -- At least 50 prisoners of war were killed when the Saudi-led coalition launched a series of airstrikes overnight on a prison in Yemen's central province of Dhamar, the Houthi-controlled health ministry said in a statement early Sunday morning.

"At least 50 were killed in seven airstrikes by the coalition warplanes against the prison and 100 others wounded, as rescue teams were still searching for possible survivors under rubble," it said, adding that the death toll could rise as many injured are in critical conditions.

Meanwhile, the Houthi-run al-Masirah television reported on its website that "the targeted prison is located inside a complex of the Community College in the center of Dhamar and that the International Committee for the Red Cross (ICRC) has visited it several times."

"The prison's location is publicly known to both the ICRC and the enemy Saudi and Emirati-led coalition," the television said, citing a statement by the group's so-called Prisoners Committee.

According to the Houthis, about 170 prisoners captured while they were fighting alongside the government forces in several front lines, have been inside the targeted prison for months.

"They were about to be released within days in a prisoner swap," the Houthi TV added.

However, the Saudi-led coalition said its airstrikes overnight on Dhamar targeted "a Houthi location for hostile air defense missiles and drone storages," Saudi-owned AL Arabiya television reported on Twitter.

Dhamar is about 100 km south of the capital Sanaa. Both Dhamar and Sanaa, as well as several other northern provinces have been under Houthi's control since late 2014 after they forced Yemeni President Abd-Rabbu Mansour Hadi and his government into exile.

Saudi Arabia has been leading an Arab military coalition against Iran-allied Houthis in Yemen for more than four years in support of the internationally-recognized government of Hadi.

In Stockholm last December, the Yemeni rival parties agreed to a United Nations (UN)-brokered deal of major prisoner swap and mutual troops withdrawal from the key lifeline Red Sea port city of Hodeidah, just days after the government forces advanced into the southern outskirts of the rebel-held port city. However, both sides have failed to implement the deal.

The UN Special Envoy Martin Griffiths has been shuttling between Sanaa and Riyadh to try to rescue the Stockholm Agreement.