The six hostages, whose bodies were found in Gaza over the summer, were probably shot in February by their captors as an Israeli strike hit close to the tunnel where they were held, the military said.

February strike shows potential risks of military operations for remaining captives.

Hezbollah has claimed the first strike against Israel since a US-backed cease-fire plan came into effect less than a week ago, prompting Israeli officials to vow a strong response in the most serious threat so far to the truce with Lebanon.

Israeli forces carried out several new drone and artillery strikes in Lebanon on Tuesday, further shaking a tenuous ceasefire meant to end more than a year of fighting with Hezbollah.