Israel's recent airstrike on a Syrian military research center has complicated the Syria crisis that has been protracted for nearly two years with no signs of an end in sight.

On Monday, Syrian Defense Minister Fahd Jassem al-Freij said Israel launched the Wednesday airstrike in cooperation with armed Syrian rebels fighting government forces on the ground.

The research center in Damascus' northwestern suburb of Jumraya had been repeatedly targeted by the rebels who failed to destroy it before the Israeli air raid, the minister said, stressing that the Syrian army would do its utmost to protect the country's institutions.

Syria has said Israeli fighters sneaked into the country and hit a center for scientific research on Jan. 30. Israeli Defense Minister Ehud Barak acknowledged the strike Sunday.

Iran, a staunch ally of President Bashar al-Assad throughout the Syria crisis, condemned Israel on Monday, warning that it would regret its airstrike.

Saed Jalili, head of Iran's Supreme National Security Council, who was in Damascus on a visit, said that Iran would use all its international relationships to support Syria, adding that Syria is an important part of the Islamic world on which no aggression would be allowed.

For its part, Israel dismissed all the threats from Syria and Iran.

"Israel is not seriously concerned about Iran's or Syria's latest bluff and there is no alert in Israel about the latest round of threats, but we are prepared to respond to any aggression, as we know Iran has the capability and intention of attacking Israel," Israeli Foreign Ministry spokesman Yigal Palmor told Xinhua.

According to a UN report, since the Syria conflict broke out in March 2011, more than 60,000 people, mostly civilians, have been killed, and more than 4 million people have been left in need of humanitarian assistance.

The United Nations Children's Fund (UNICEF) said on Monday that a large-scale operation is under way in Syria to secure safe water supplies for more than 10 million people.

The first four trucks carrying 80 tons of sodium hypochlorite water chlorination supplies crossed the Jordanian border into Syria last Sunday, heading for Aleppo, Hama, Idleb and Homs.

About 420,000 people, half of them children, need urgent humanitarian aid in Homs, UNICEF said last week.

Meanwhile, there have been no signs of reconciliation between the Syrian government and the opposition.

Opposition leader Moaz Alkhatib on Monday urged the government to start talks for its departure from power, a motion unlikely to be accepted by the Syrian government, which has yet to respond.

Diplomatic efforts to end the Syria crisis persist. On Feb. 6-7, a summit of the Organization of Islamic Cooperation will be held in Cairo, with the Syrian situation high on its agenda.