British Foreign Secretary William Hague said Sunday that apparent Israeli air strikes on Syria showed that peace across the whole region was under threat, and reinforced the need to lift an arms embargo on Syrian rebels.

Hague's comments came after a senior Israeli official said that the Jewish state carried out a pre-dawn attack near Damascus on Sunday targeting Iranian missiles destined for Lebanon's Hezbollah.

"We don't have any official confirmation but of course there have been some sources in Israel saying that this has been an Israeli airstrike -- I will wait before commenting in detail on that for official confirmation," Hague told Sky News.

"But what I can say is that these events, and many other events of recent days, do show increasing danger to the peace of that entire region from the Syria crisis just getting worse and worse."

Hague added: "Lebanon is constantly threatened by being destabilised, huge numbers of refugees are crossing the border, Jordan is under incredible strain.

"And Israel has made very clear that it will act if it believes that important weapons systems are being transferred to Hezbollah."

Hague said that "Israel will act to protect its national security, we do have to respect that."

The Israeli strike on Sunday was the second on Syrian soil in three days, following an attack near Damascus airport on Friday which also struck Iranian arms destined for the Lebanese Shiite movement.

Iran condemned the strikes, which witnesses in Damascus said were like an earthquake.

The British foreign minister said the growing threat to peace in the region from the Syria crisis showed the need to increase assistance to the Syrian opposition.

He added that the "longer this goes on the stronger the case becomes for lifting the arms embargoes" against the Syrian opposition.

Britain is pushing the EU to lift an arms embargo on Syria, which comes up for renewal at the end of May.

Hague meanwhile reiterated that there were "credible reports of chemical weapons being used against" the Syrian people, although he was not pressed on whether that had passed the West's "red line" for intervention.