Iran has launched dozens of drones at targets in Israel, a spokesperson for the Israel Defence Forces has said.
The army's spokesman, Rear Admiral Daniel Hagari, said it would take several hours for the aircraft to arrive.
Three security sources told Reuters that a number of drones were seen flying from the direction of Iran over Iraq's Sulaymaniya province.
Iraq also announced shutting down its airspace and suspending all air traffic on Saturday, Iraq's transport ministry told the country's state-owned news agency.
Iran's Revolutionary Guards confirmed it had launched dozens of drones and missiles against specific targets in Israel, Iranian state media quoted a statement by the elite force as saying.
Jordan said its air defences were ready to intercept and shoot down any Iranian drones or aircraft that violate its airspace, two regional security sources told Reuters.
Prime Minister Rishi Sunak condemned “in the strongest terms” Iran’s “reckless attack” against Israel, saying the UK “will continue to stand up for Israel’s security and that of all our regional partners”.
In a statement on Saturday night, Mr Sunak said: “These strikes risk inflaming tensions and destabilising the region.
“Iran has once again demonstrated that it is intent on sowing chaos in its own backyard.
“The UK will continue to stand up for Israel’s security and that of all our regional partners, including Jordan and Iraq.
“Alongside our allies, we are urgently working to stabilise the situation and prevent further escalation. No-one wants to see more bloodshed.”
Israel has been on heightened alert since an airstrike last week killed two Iranian generals in Syria.
Iran accused Israel of being behind the attack and vowed revenge, but Israel did not claim responsibility for the operation.
Iran’s supreme leader Ayatollah Ali Khamenei said Israel “must and shall be punished” for an operation that he claimed amounted to an attack on Iranian soil.
President Joe Biden will meet with national security officials and Cabinet members at the White House on Saturday afternoon to discuss the latest developments, the White House said.
Israeli Prime Minister Benjamin Netanyahu said the country's defence systems have been deployed.
“We are ready for any scenario, both defensively and offensively. The State of Israel is strong. The IDF is strong. The public is strong.
"I established a clear principle - whoever hurts us, we hurt him. We will protect ourselves from any threat and we will do so with coolness and determination," he said.
On Friday, Mr Biden reaffirmed Washington’s commitment to protecting Israel from an Iranian attack.
“We are devoted to the defense of Israel. We will support Israel. We will help defend Israel and Iran will not succeed,” he said.
Iran’s special forces on Saturday seized a commercial ship with links to Israel, the vessel’s management said.
The MSC Aries, which is linked to Israeli billionaire Eyal Ofer, said in a statement that it was boarded by the third party while off the coast of the United Arab Emirates.
