Israeli warplanes have attacked a target close to the Syrian-Lebanese border following several days of heightened warnings from government officials over Syria's stockpiles of weapons.

Syrian state television said that military command had confirmed a "scientific research centre" north-west of Damascus was struck at dawn on Wednesday, causing damage. Two people were killed and five wounded in the attack on the site, which was engaged in "raising the level of resistance and self-defence".

Earlier, diplomatic and security sources were cited in media reports as saying a convoy of trucks had been struck close to the Syrian-Lebanese border. The Israeli Defence Forces said it had no comment.

Lebanese media claimed that a dozen IDF fighter planes had flown sorties over Lebanon's airspace from Tuesday afternoon until Wednesday morning.

A Lebanese army statement, quoted by local news agencies, said: "Four Israeli planes entered Lebanese airspace at 4.30pm on Tuesday. They were replaced four hours later by another group of planes, which overflew southern Lebanon until 2am, and a third mission took over, finally leaving at 7.55am on Wednesday morning." The IDF also declined to comment on these reports.

It was also reported that the IDF's intelligence chief, Major-General Aiv Kochavi, arrived in Washington on Tuesday for private talks with the US chairman of the joint chiefs of staff, Martin Dempsey, at the Pentagon.

Israel has publicly warned that it would take military action to prevent the Syrian regime's chemical weapons falling into the hands of Hezbollah in Lebanon or "global jihadists" fighting inside Syria. Israeli military intelligence is said to be monitoring the area round the clock via satellite for possible convoys carrying weapons.

Hezbollah is also believed to have extensive stockpiles of conventional weapons in warehouses inside Syria. Hezbollah's leader, Hassan Nazrallah, "wants to remove everything from Syrian soil to Lebanon", said Amnon Sofrin, a former head of intelligence in the Israeli intelligence agency Mossad. Israel, he added, was "looking very carefully at convoys heading from Syria to Lebanon".

The Israeli prime minister, Binyamin Netanyahu, was reported earlier this week to be conducting intense security consultations on the possible response to the movement of weapons.

The deputy prime minister, Silvan Shalom, told Army Radio on Sunday: "If there is a need, we will take action to prevent chemical weapons from being transferred to Islamic terror organisations. We are obligated to keep our eye on it at all times, in the event chemical weapons fall into Hezbollah's hands."

Israel's concern over the civil war in Syria has mounted over recent months as Bashar al-Assad's regime has come closer to collapse and fighting has bordered on the Israeli-occupied Golan Heights. Although Israel has been technically at war with Syria since 1967, the Golan Heights has been mostly quiet since Israel occupied it almost 46 years ago.

But Israel fears that the implosion of the Assad regime could herald an Islamist Syria, which could seek to reignite hostilities with its neighbour.

Alex Fishman, defence analyst for the newspaper Yedioth Ahronoth, wrote earlier this week: "In the light of Assad's increasingly unsteady status, Hezbollah figures have understood that [its stockpiles of conventional] weapons cannot remain there. And as soon as these weapons reach Lebanon, they are swallowed up in secret underground stockpiles. Looking for them will be like searching for a needle in a haystack.

"If chemical weapons are brought into Lebanon, Israel will probably not hesitate – and will attack."

According to Sofrin, the Israeli military would be more inclined to deploy "specialist skilled units" on the ground to secure depots of chemical weapons, rather than use air strikes, which risked dispersing chemicals over a wide area. But any such operation would be complicated and risky, he added.

Israel's primary concern was to prevent Hezbollah acquiring chemical warheads that it could mount on existing missiles, he said.

Netanyahu told Sunday's cabinet meeting Syria was "increasingly coming apart". He added: "The reality is developing apace. In the east, north and south, everything is in ferment, and we must be prepared: strong and determined in the face of all possible developments."

In the past few months, errant shells from fighting in Syria have landed in the Golan Heights, prompting Israel to lodge formal complaints with the United Nations. In November, Israeli forces fired tank shells at Syrian artillery units, causing casualties, over two consecutive days after a mortar shell landed close to an Israeli army post.

Netanyahu recently announced plans to build a steel security fence along the armistice line in the Golan Heights, similar to the one constructed on the Israel-Egypt border.