New Delhi, April 9 -- The fragile ceasefire between Iran and the United States appeared to be weakening on Thursday, as Tehranthreatening to resume hostilities as Israel continued heavy strikes in Lebanon.

Washington and Tehran on Tuesday both claimed 'victory' after agreeing to a two-ceasefire and negotiations aimed at ending the Middle East conflict. But things went soar as Israel carried out deadly strikes on neighboring Lebanon -- including in densely packed central Beirut, biggest attack since the Iran-backed militant group Hezbollah joined the war in early March. At least 182 people were killed and nearly 900 wounded on Wednesday, the Lebanese Health Ministry said.

Hezbollah responded on Thursday, saying it had fired rockets towar...