Israel and Lebanon will hold talks next week in Washington, a State Department official said on  Thursday, as concerns grow that fighting involving Hezbollah could cause the fragile US-Iran truce to unravel. Israel's heaviest bombardment on Lebanon since Hezbollah entered the Middle East war in early March killed hundreds on Wednesday, shaking the ceasefire between Washington and Tehran less than 48 hours after it came into force.

"We can confirm that the Department will host a meeting next week to discuss ongoing ceasefire negotiations with Israel and Lebanon," the official said, confirming an earlier account from a source familiar with the diplomatic efforts.

Israel's Prime Minister Benjamin Netanyahu had earlier on Thursday ordered his ministers to seek direct talks with Lebanon, pushing for Iran-backed Hezbollah's disarmament.

But a Lebanese government official told Agence France-Presse (AFP) after Netanyahu's announcement that Beirut required a truce before starting any negotiations with Israel, a day after the deadly strikes across Lebanon.

"Lebanon wants a ceasefire before starting negotiations," said the Lebanese government official, who has knowledge of the matter and requested anonymity. Neither Israel nor Lebanon have publicly confirmed the US talks for next week.

Israel's army Chief of Staff Eyal Zamir visited ground troops inside Lebanon on Thursday, telling them Hezbollah suffered a "heavy blow" from the strikes a day earlier.

Netanyahu's order for direct negotiations with Lebanon's government was focused on disarming Hezbollah and establishing peace, according to a statement from his office, but he offered no immediate respite from the aerial attacks. A Hezbollah lawmaker later reiterated his group's "rejection of any direct negotiations between Lebanon" and Israel.