DUBAI, Aug 1 (Reuters) - Top Iranian officials will meet the representatives of Iran's regional allies from Lebanon, Iraq and Yemen on Thursday to discuss potential retaliation against Israel after the killing of the Hamas leader in Tehran, five sources told Reuters.

The region faces a risk of widened conflict between Israel, Iran and its proxies after Ismail Haniyeh's assassination in Tehran on Wednesday and the killing of Hezbollah's senior commander on Tuesday in an Israeli strike on the outskirts of the Lebanese capital Beirut.

Representatives of Iran's Palestinian allies Hamas and the Islamic Jihad, as well as Yemen's Tehran-backed Houthi movement, Lebanon's Hezbollah and Iraqi resistance groups will attend the meeting in Tehran, said the sources, who declined to be named due to the sensitivity of the issue.

"Iran and the resistance members will conduct a thorough assessment after the meeting in Tehran to find the best and most effective way to retaliate against the Zionist regime (Israel)," said a senior Iranian official, with direct knowledge of the meeting.

Another Iranian official said Supreme leader Ayatollah Ali Khamenei and senior members of Iran's elite Revolutionary Guards will attend.

"How Iran and the resistance front will respond is currently being reviewed ... This will certainly happen and the Zionist regime (Israel) will undoubtedly regret it," General Mohammad Baqeri, Iran's armed forces chief of staff, told state TV on Thursday.

Iran and Hamas have accused Israel of carrying out the strike that killed Haniyeh hours after he attended the inauguration of Iran's new president in Tehran on Wednesday.

But Israeli officials have not claimed responsibility for the attack that drew threats of revenge on Israel and fuelled further concern that the Israel-Hamas conflict in Gaza was turning into an all-out war in the Middle East.

Israeli air force chief Tomer Bar, speaking at a military graduation ceremony in Israel late on Wednesday, warned Israel will act against anyone planning to harm its citizens.

"We are also strongly prepared in defence. Hundreds of aerial defence soldiers, along with air control personnel, are stationed across the country with the best systems, ready to carry out their mission," said Bar.

Haniyeh and the leader of the Islamic Jihad, Ziad al-Nakhala, as well as senior representatives of Yemen's Tehran-backed Houthi movement and Lebanon's Hezbollah, attended the inauguration ceremony for Iran's new president in Tehran on Tuesday.

Hezbollah deputy leader Naim Qassim and lawmaker Hassan Fadlallah were in Iran for the inauguration and have remained there for the funeral and meeting, sources familiar with Hezbollah’s thinking said.

Photo from Reuters