A bridge near the holy city of Qom and another carrying a railway line in the central city of Kashan were struck, according to regional officials quoted by state media.

Two people were killed and three were injured in Kashan, senior regional security official Akbar Salehi said, according to Iran's IRNA news agency.

A key highway in northern Iran connecting the main northern city of Tabriz with Tehran via Zanjan was also temporarily closed after a hit around 90 kilometres (55 miles) outside of Tabriz, IRNA and Fars agencies reported.

Fars and the Mizan news agencies also reported a strike on railway tracks in Karaj, outside Tehran, with images showing Red Crescent rescuers carrying an injured man on a stretcher.

All trains were cancelled to and from Iran's second city of Mashhad on Tuesday following a warning from Israel against using the railways.

As reports of the damage emerged from Iran, the Israeli military said it struck "eight bridge segments that were utilised by the Iranian terror regime's Armed Forces for transporting weapons and military equipment in several areas across Iran, including Tehran, Karaj, Tabriz, Kashan, and Qom".

According to Iran's ISNA news agency, there were also power outages in parts of the cities of Karaj and Fardis after power transmission lines and a power substation were knocked out of service by airstrikes.

US President Donald Trump warned Tuesday that "a whole civilization will die" in Iran if a midnight deadline to reach a deal to reopen the Strait of Hormuz was not met.

The US also reportedly hit military targets on the key Iranian oil export hub of Kharg Island on Tuesday.

"Several explosions" were reported there by Iran's Mehr news agency, while Fox News reported that US airstrikes had targeted bunkers, radars and ammunition stores, not energy infrastructure.

Kharg Island is used to handle around 90 percent of Iran's oil exports.

On March 13, the United States said it had already bombed more than 90 targets there, without hitting the pumping facilities.