U.N. Secretary General Ban Ki-moon on Saturday demanded that both sides battling for the strategic Syrian town of Qusayr allow civilians to flee the fighting, his spokesman said.

"He urges all sides to do their utmost to avoid civilian casualties," Ban's spokesman, Martin Nesirky, said in a statement.

The United States on Wednesday demanded the immediate withdrawal of Hizbullah fighters from Syria, saying their active role in combat there was an "extremely dangerous escalation."

"This is an unacceptable and extremely dangerous escalation. We demand that Hizbullah withdraw its fighters from Syria immediately," State Department spokeswoman Jen Psaki said.

Twenty-two Hizbullah members were killed in fighting alongside Syrian government forces against rebels for control of the town of Qusayr, a source close to the Lebanese group said on Sunday.

"There were 22 killed on Saturday. Nine bodies were repatriated the same day and the rest on Sunday," the source said, declining to be named.

Syrian regime troops backed by Hizbullah fighters attacked the village of Hamadiyeh north of Qusayr of Wednesday, one of the last remaining rebel positions in the area, activists said.

"The Syrian regime is receiving help from Hizbullah and Iran. That's an increasing threat to regional stability," British Foreign Secretary William Hague told reporters at the Friends of Syria talks in Jordan's Amman.

The U.N.'s children's agency warned Tuesday that up to 20,000 civilians, mainly women and children, could be trapped by harsh fighting in the Syrian town of Qusayr.

"The situation is desperate," UNICEF spokeswoman Marixie Mercado told reporters in Geneva.

The rebel Free Syrian Army on Monday claimed that Hizbullah elusive commander Mustafa Badreddine -- who is accused of involvement in former premier Rafik Hariri's murder – is leading the group's operations in the Syrian town of Qusayr.

“It has been confirmed that Mustafa Badreddine is present on Qusayr's front where he is leading Hizbullah's operations,” said a statement issued by the FSA.

Two men were killed and contact was lost with at least 18 others in the Syrian town of al-Qusayr near the border with Lebanon, LBCI television reported on Thursday.

"The men who hail from the northern cities of Tripoli and Dinniyeh have left Lebanon to participate in the battles in al-Qusayr's countryside”, sources close to the Syrian opposition told LBCI.

A Katyusha rocket fired from Syrian territory landed in the middle of the Hermel town of al-Qasr in the Bekaa on Sunday, state-run National News Agency reported.

The agency did not say whether or not the shelling caused any casualties or damage.

Controversial Islamist cleric Sheikh Ahmed al-Asir on Wednesday returned to Lebanon after crossing into the war-torn Syrian area of Qusayr to “support the real heroes” of the armed Syrian opposition.

“My visit to Qusayr's countryside was in support of the true heroes and to coordinate with them and examine the situation,” Asir said on the social networking website Twitter.

Islamist cleric Sheikh Ahmed al-Asir, the imam of Sidon's Bilal bin Rabah Mosque, on Monday announced the creation of the “Free Resistance Brigades,” urging whoever is capable of heading to Syria to go there to aid “the oppressed” in Qusayr and Homs.

Asir called on “all the Lebanese who fear attacks by Iran's party (Hizbullah) in Lebanon to arm themselves and form 5-member secret cells in order to be ready to exclusively defend themselves and their families should the need arise.”