Explosions rocked Iran's central Isfahan province on Friday, according to state media, while U.S. officials told American news outlets that Israel carried out a retaliatory strike on the Islamic republic.

The attack comes less than a week after Tehran launched a barrage of more than 300 drones and missiles in its first-ever direct assault on Israel's soil. That unprecedented onslaught was itself a reprisal for an earlier strike in Syria widely blamed on Israel.

The World Health Organization voiced alarm Thursday at the growing spread of H5N1 bird flu to new species, including humans, who face an "extraordinarily high" mortality rate.

"This remains I think an enormous concern," the UN health agency's chief scientist Jeremy Farrar told reporters in Geneva.

The World Health Organization on Thursday announced a new, catch-all terminology for pathogens that transmit through the air, erasing a distinction that caused dangerous confusion during the Covid pandemic.

During the Covid-19 crisis the standoff between experts arguing over whether the SARS-CoV-2 virus spread through droplets or through an aerosol mist proved a crucial public health challenge.

A senior Revolutionary Guards general threatened on Thursday to target Israel's "nuclear facilities" if it strikes Iranian atomic sites, state media reported, anticipating retaliation for Tehran's unprecedented weekend attack.

Israel's military chief has vowed a response to the Iranian aerial attack, which was mostly intercepted, while world leaders have urged de-escalation.

Hundreds of Gazans found rare respite at the beach this week from more than six months of traumatizing Israeli bombardments in the Palestinian territory.

After temperatures suddenly soared, children paddled in the sea and their friends played ball games on the sand around Deir el-Balah in the center of the coastal strip -- but the war was never far away.

Israel launched more deadly strikes on besieged Gaza on Thursday as world powers watched nervously whether the country would retaliate against a weekend attack by its arch enemy Iran.

German airline giant Lufthansa on Thursday extended its suspension of flights to and from Tehran and Beirut to the end of April and said its planes would continue avoiding Iranian airspace.

"Our flights to Tehran and Beirut are cancelled up to and including 30 April and we are still not using Iranian airspace until the same date," a spokesman for the airline told AFP.

Israel's Prime Minister Benjamin Netanyahu said his country reserved the right to protect itself after Iran's unprecedented attack, and that it alone would decide how to do so.

Iran launched more than 300 drones and missiles at Israel over the weekend in an attack that caused little damage after most of the projectiles were intercepted.

Two Hezbollah members were killed Thursday in an overnight strike on the southern border town of Kfarkila, as tensions flared on the Lebanese-Israeli border.

Israeli warplanes and artillery also heavily bombed the town of al-Khiam, including with white phosphorus bombs, while a drone targeted a house in Markaba.

As regional tensions run high, Iran paraded drones, missiles and soldiers on Wednesday to show it is ready for any response from Israel after launching an unprecedented attack on its bitter enemy.

The Islamic republic carried out its first-ever direct attack on Israel at the weekend in response to an April 1 air strike on its consulate in Damascus which has been widely blamed on Israel.