But only two of the deaths have been made public, raising suspicions the officers may have been assassinated by Iran's enemies.
The unusually large number of deaths among senior IRGC commanders followed a disclosure by Israel's military chief of staff, Lt. Gen. Benny Gantz, in April that covert Special Forces operations against "enemy countries" were becoming more intense.
There doesn't appear to be any solid evidence the Israelis were involved in the deaths of the Revolutionary Guard chiefs.
But Gantz told the Yediot Ahronot daily, "You almost won't find a point in time where something isn't happening somewhere in the world. I'm escalating all those special operations."
He didn't say which countries were being targeted. But in recent years Israel has been mounting clandestine operations against Iran and its contentious nuclear program, which Israeli leaders see as an existential threat.
Intelligence Online, a Paris Web site that specializes in global intelligence and security issues, identified the two officers whose deaths were acknowledged by the Tehran regime as Gen. Gholam Reza Qassemi, former commander of the 92nd Armored Division, and Gen. Mohammad Ali Mousavi, leader of a commando regiment in the southwestern city of Ahwaz, a key oil center.
Intelligence Online said there was speculation some of the deaths could have resulted from turf wars within the increasingly powerful IRGC over control of sections of the vast economic empire the IRGC has built up in recent years.
The IRGC is reported to operate widespread illegal economic networks, including smuggling, that have made it one of the most crucial economic forces in the country.
This, on top of its growing political power, has raised suggestions both inside and outside Iran that the IRGC, formed by the late Ayatollah Ruhollah Khomeini to protect the 1979 Islamic Revolution, may seek to take control at some point.
Intelligence Online said the Gen. Ahmed Mansouri, one of the representatives of Supreme Leader Ayatollah Ali Khamenei within the IRGC leadership, also died recently, supposedly from a heart attack.
It also said two senior colonels, Najaf Ali Khirallahi and Nassif Pour, were killed in car accidents.
Intelligence Online said other senior IRGC officials, identified as Wafa Ghafarian, 52; Abbas Mehri, 53; Ahmed Siafzadeh, 55; Mansour Tourqan, 50; and Ahmed Soudaker, 51, also passed away recently, with no official explanation.
"Khamenei has not publicly expressed his condolences, which are usually widely reported in the Iranian press," the Web site observed.
Israel and the United States were allegedly involved in cyberattacks using the powerful W32.Flame malware against Iranian targets, including the big Kharg Island oil terminal in the northern Persian Gulf, in April.
Israeli leaders have dropped strong hints that the Jewish state was responsible for the new data-stealing computer virus, much more dangerous than the Stuxnet worm used to attacks Iran's uranium enrichment program in 2009-10.
The New York Times reported that U.S. President Barack Obama ordered the sophisticated cyberattacks on Iran's computer systems, in conjunction with Israel, soon after he took office in a bid to cripple the Islamic Republic's infrastructure.
Recent events have been played out amid crucial meetings between Iran and U.S.-led powers seeking to convince Tehran to halt uranium enrichment and curtail its nuclear program.
Meetings in Istanbul in April and in Baghdad in May failed to produce an agreement. Another meeting is scheduled but the prospect of a deal seems remote.
In the meantime, the Obama administration has disclosed Iranian plots to kill U.S. diplomats and their families in Azerbaijan, Iran's Muslim northern neighbor and increasingly an ally of Israel.
Also, U.S. and Israeli officials have said other plots have been uncovered involving Iran and its Lebanese surrogate, Hezbollah, in India, Thailand, Turkey, Pakistan and the former Soviet republic of Georgia.
On May 30, Yoram Cohen, head of Israel's domestic security service, known as Shin Bet, claimed Iranian-funded militants have stepped up attempts to attack Jewish targets around the world in recent months.
He stressed that only a fraction of these operations have been publicized.
On May 11, a senior Israeli officer said security around top military commanders and military delegations traveling overseas has been "significantly stepped up" because of Iranian and Hezbollah plots.