"The passage for all commercial vessels through Strait of Hormuz is declared completely open for the remaining period of ceasefire," Araghchi said on X.

It was not clear whether he was speaking of the 10-day truce agreed by Lebanon and Israel that went into effect at midnight or an earlier two-week truce between Iran and the United States that began on April 8.

Iran, which sent shockwaves through the global economy by essentially blocking passage through the crucial Strait, had made the extension of a ceasefire to Lebanon a condition of opening the waterway, state media reported.

Lebanon was drawn into the broader war launched by the United States and Israel on February 28 when Hezbollah attacked Israel in support of Iran, its key ally.

An Iranian senior military official told the state broadcaster that only civilian vessels would be allowed passage through designated routes and with permission of the navy of Iran's Islamic Revolutionary Guard Corps.

"The passage of military vessels through the Strait of Hormuz remains prohibited," the official said.

US President Donald Trump welcomed the Iranian announcement that the narrow waterway would be open, but said the US naval blockade of Iranian ports would remain in place until a peace deal with Tehran was reached.

"The naval blockade will remain in full force and effect as it pertains to Iran, only, until such time as our transaction with Iran is 100% complete," Trump said on his Truth Social network, adding that "this process should go very quickly".

Oil prices that had spiked during the supply disruptions plunged after the Iranian announcement of opening the Strait.