Syria on Thursday warned that its forces would fire into Lebanon if "terrorist gangs" continued to infiltrate the country, in a letter of protest to Lebanon.

"These past 36 hours, armed terrorist gangs have infiltrated Syrian territory in large numbers from Lebanon," the Syrian foreign ministry said in the letter carried by Syria's news agency SANA.

Syria's President Bashar Assad Thursday congratulated Pope Francis on his election, highlighting his role as head of the Roman Catholic church in "spreading love" in the world.

Assad's statement comes two years into a spiraling conflict in Syria that the United Nations estimates has left some 70,000 people dead.

Army Commander General Jean Qahwaji on Thursday reassured that the circumstances of the 1975-1990 civil war “will not be repeated,” stressing that the army is determined “more than ever” to prevent a spillover of the Syrian crisis into Lebanon.

In his instructions to the army's top generals during a meeting held in Yarze, Qahwaji underlined the military institution's “determination, more than ever, to spare Lebanon the repercussions of regional conflicts and to confront any party seeking to incite sectarian strife with the aim of undermining state authority and national unity.”

Israel's military intelligence chief on Thursday said the regime of Syrian President Bashar Assad has contingency plans to use chemical weapons as it battles insurgents.

Speaking at Israel's annual Herzliya Conference on security and policy, Major General Avi Kohavi said Assad was still in control of his stockpile of chemical weapons, which the Jewish state fears could fall into the hands of militants.

Three Russia warships docked on Thursday in Beirut Port, and al-Mayadeen television reported that they will stay in Lebanese waters for three days before departing to Syria.

"The warships carry 700 soldiers and are planning to stay in Mediterranean waters for three days,” al-Mayadeen said, adding that they will then sail to the Syrian port of Tartus.

Chinese-made missiles have been used to shoot down two Syrian army helicopters, state media reported Thursday, adding their performance could boost the international sales appeal of Chinese weapons.

The Global Times, a tabloid with close links to the ruling Communist Party, said a pair of videos posted on the Internet by Free Syrian Army rebels showed two Mi-8/17 helicopters being shot down by Chinese shoulder-launched missiles.

The Philippines said Thursday it would keep its contingent of United Nations peacekeepers in the Golan Heights, after Syrian rebels held 21 of them hostage for three days last week.

"The Philippine contingent to the UNDOF (U.N. Disengagement Observer Force) would remain stationed in the Golan Heights to perform its obligation in the name of peace," foreign department spokesman Raul Hernandez told reporters.

A divisive debate over Lebanon's electoral law may delay parliamentary elections scheduled for June 9, stoking fears of instability in a country already rattled by the conflict in neighboring Syria.

Nominations opened on Monday but no candidate has yet been registered. Meanwhile, rival political groups have quibbled over how legislative power should be shared out in the multi-confessional country.

The U.N. Security Council must refer war crimes committed by both sides in Syria's two-year conflict to the International Criminal Court, Amnesty International said on Thursday.

"How many more civilians must die before the U.N. Security Council refers the situation to the prosecutor of the International Criminal Court so that there can be accountability for these horrendous crimes?" asked Ann Harrison, Amnesty's deputy director for the Middle East and North Africa.

The U.N. has halted peacekeeping patrols in the Golan Heights amid fears that fallout from the Syrian war could cause more countries to withdraw from its force, diplomats said Wednesday.

The abduction last week of 21 Philippine members of the United Nations Disengagement Observer Force (UNDOF), which has monitored a ceasefire zone between Syria and Israel since 1974, has heightened security fears.