Israel's air strikes on Syria could add pressure to the Obama administration to intervene in Syria, a key Republican politician has said.

Hours after Israeli jets bombed Syria today for the second time in 48 hours, several top US politicians voiced concern over the uncertainty in the Middle East.

Republican Senator John McCain said the latest Israeli air strikes will just put more pressure on the administration to act.

President Barack Obama has said he has no plans to send ground troops to Syria.

UN Secretary-General Ban Ki-moon has voiced alarm at reports Israel has struck targets inside Syria.

But he said the United Nations was unable to confirm whether any such attacks had taken place.

Mr Ban "calls on all sides to exercise maximum calm and restraint, and to act with a sense of responsibility to prevent an escalation of what is already a devastating and highly dangerous conflict".

Earlier, Syrian state media said Israeli missiles hit a scientific research centre on the outskirts of the capital, Damascus.

Residents reported huge explosions and claimed military bases in the area were also hit.

A Western intelligence source said the overnight Israeli strike targeted Iranian-supplied missiles to the Lebanese Hezbollah group.

If confirmed, it would be the second such Israeli attack on Syria in three days.

Israeli radio has reported that a senior security official has confirmed that an attack took place.

Iran has condemned the incident and urged countries in the region to stand against the action.

Yesterday, there were also reports that Israel carried out an air strike targeting a shipment of missiles in Syria bound for Hezbollah in neighbouring Lebanon.