Officials in Iran's western city of Khorramabad have denied an attack took place after residents were jolted by an overnight explosion.
Locals reported hearing a “terrible sound” and taking cover in the city, in Lorestan province, late on Monday amid what was initially suspected to be an earthquake.
Authorities have since denied an earthquake or an explosion took place.
The city is near a major base affiliated with Iran's Islamic Revolutionary Guard Corps, which houses an underground facility for ballistic missiles and drones.
Lorestan officials denied an explosion took place in an interview with the IRGC-affiliated Tasnim news agency, and said media reports on the blast aimed to “disturb” the public.
Some Iran observers have claimed the explosion was an Israeli attack on the Imam Ali base, although neither Tehran nor Israel have confirmed that.
Iran blamed Israel for a January drone attack on a weapons depot in Isfahan.
Israel has vowed to curb Iranian nuclear activity and its regional influence, and is suspected to be behind regular attacks on Iran-linked sites in Syria.
Suspected Israeli attacks have put airports in Aleppo and Damascus out of service on several occasions in recent months.
While Israel rarely admits to the strikes, it has repeatedly said it would act against Tehran.
It has recently acknowledged action in both Syria and Iran itself.
The army admitted it struck an Iran-backed weapons convoy on the Iraq-Syria border last December.
In June, Israel's Mossad intelligence agency said it abducted a man inside Iran, who was plotting to kill Israelis in Cyprus upon orders from the IRGC.
Earlier this month, Israeli Defence Minister Yoav Gallant said Iran was building an airport in southern Lebanon to use as a base for attacks against Israel.