July 24 (UPI) -- U.S. officials have condemned Russian and government airstrikes in northern Syrian that killed at least 59 civilians.

Air and ground strikes by Russian and Syrian forces Monday killed 59 people, including more than three dozen civilians at a marketplace in the northwest town of Maaret al-Numan, according to the Syrian Observatory for Human Rights.


Three children and three women were among the civilian dead in what the Britain-based organization called the rebel-held province's worst massacre since April, when the Russian and Syrian regimes violated a cease-fire agreement.

U.S. State Department Spokeswoman Morgan Ortagus said Tuesday continued airstrikes over the past three months have destabilized the region and displaced at least 330,000 in the past few months while demonstrating Syrian President Bashar al-Assad believes in a military solution to the ongoing civil war.

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"These attacks by Russia and the Assad regime continue to deliberately strike civilian infrastructure -- which is a blatant violation of international law -- they hit medical facilities of which coordinates have been shared with the U.N., in an effort to protect civilians," she said in a statement. "Attacks by Russia and the Assad regime also continue to kill and maim humanitarians such as ambulance drivers, health workers and White Helmets volunteers."

Russia's Defense Ministry denied accusations it had carried out the attack on Maaret al-Numan, calling it in a statement "a fake news story," Russia's state-run TASS reported.

"The Russian air task force's aviation did not accomplish any missions in that area of the Syrian Arab Republic," the ministry said.

U.S. officials said the strikes were acts of "desperation."

"We call on Russia and the Assad regime to return to a cease-fire in the area and allow for unhindered access to address the humanitarian disaster created by the airstrikes," Ortagus said.

The province of Idlib has been under immense pressure due to these airstrikes, causing the heads of 11 global humanitarian organizations in late June to warn that Idlib was on "the brink of a humanitarian nightmare unlike anything we have seen this century."

"Everything needs to be done to protect civilians," said Najat Rochdi, a senior humanitarian adviser to the U.N special envoy for Syria. "Universal principles and values must prevail when so many innocent lives are at stake."