Israeli warplanes carried out late on Thursday their most intense strikes on southern Lebanon in nearly a year of war, heightening the conflict between Israel and the Lebanese armed group Hezbollah, amid calls for restraint.

The White House said a diplomatic solution was achievable and urgent, and Britain called for an immediate cease-fire between Israel and Hezbollah.

The U.S. is "afraid and concerned about potential escalation," White House spokesperson Karine Jean-Pierre told a briefing.