Syria fighting escalates in last opposition stronghold

May 7 (UPI) -- Fighting between pro-Assad forces and the opposition in northwestern Syria Tuesday marked a new wave of violence in the region, forcing civilians to again flee for their lives.

Syrian troops took control of a village and a key strategic hill in the region during the latest wave of fighting that started April 30 in the opposition's last stronghold in the country.

It marked the worst fighting since September when Russia and Turkey agreed to establish a demilitarized zone in the Idlib Province in hopes of de-escalating the fighting among the government forces and rebels.

The Syrian Observatory for Human Rights said nine civilians died in the escalated clashes. Since Monday, at least 53 fighters died in confrontations.

The observatory said two children and two women were among the dead when Syrian government planes bombed Kafr Zita in the northern portion of Hama. Civilians also died in a raid on al-Zerba by Russian soldiers, and the bombing of the villages of Shannan, Morek and Om al-Nur.

"In the same context, the Syrian Observatory for Human Rights learned that the regime forces managed after midnight to regain control of the strategic hill of Tal Osman north of Hama," the group wrote.

Syria has been engulfed in a civil war since 2011, when protests against the Bashar al-Assad regime connected with the Arab Spring were met with armed suppression by the government.

In the meantime, U.N. Secretary-General Antonio Guterres Monday called for measures to be taken to protect civilians and to prevent further displacement.

"He is alarmed by reports of aerial attacks on population centers and civilian infrastructure resulting in hundreds of civilian dead and injured and over 150,000 newly displaced persons," Guterres' spokesman Stephane Dujarric said in a statement.

"On 5 May, three health facilities were reportedly hit by airstrikes, bringing the total to at least seven struck since 28 April. ....The secretary-general urges all parties to uphold international humanitarian law and protect civilians ... as the holy month of Ramadan begins," the statement continued.

The state-run Syrian Arab News Agency reported the pro-government soldiers attacked "terrorist groups" and their supply routes in Hama, destroying their gathering locations on the outskirts of Kafr Zita and al-Arba'ain. The opposition suffered heavy losses in the attack.