Iran criticized Egypt on Wednesday for delays in issuing permits to bring in aid to Gaza and to transport wounded women and children out of the area for medical treatment.
Egypt's military-backed government, at odds with Gaza's Islamist rulers Hamas, has reinforced an Israeli blockade of the narrow strip of territory, in effect cutting off all routes to residents who have spent three weeks under Israeli bombardment.
To get aid across, Iran would have to fly its shipments to Egypt and then cross by land through the Rafah border into Gaza. The only other option would be to go through Israel, an unlikely scenario for Iran.
Iran's Deputy Foreign Minister Hossein Amir Abdollahian said on Wednesday 100 tons of humanitarian aid had been waiting for days for Egypt's approval to be taken into Gaza.
"For the past days we have provided the Egyptian foreign ministry and their interest section in Tehran with information on shipment of humanitarian goods and the list of 57 severely wounded Palestinian women and children we have offered to bring here for medical treatment, but they have yet to issue a permit," he told the official IRNA news agency.
"This is unacceptable. We hope Egypt would hold up to its Arab, Islamic and humanitarian responsibilities against Zionist crimes in Gaza," said Abdollahian, who visited Lebanon earlier this week to discuss the war in Gaza with Lebanese and Hezbollah leaders.
Egyptian foreign ministry officials were not immediately available for comment.
Since former Islamist president Mohamed Morsi was ousted last July, Egypt has destroyed hundreds of border smuggling tunnels that were the financial lifeline of both Gaza and Hamas.
The move reinforced an Israeli blockade in place since Hamas, which is sworn to Israel's destruction, won Palestinian parliamentary polls in 2006.
Egypt views Hamas as a security threat because it is an offshoot of Morsi's Muslim Brotherhood.
Iranian President Hassan Rouhani's government has taken a more pragmatic line on the issue than supreme leader Ayatollah Ali Khamenei, who called on Muslim countries on Tuesday to arm the Palestinians to defend themselves.
Foreign Minister Mohammad Javad Zarif has been telephoning regional counterparts, including Egypt's Sameh Shokri on Sunday.
Relations have been sour between Tehran and Cairo since Iran's 1979 Islamic revolution when the government in Cairo gave sanctuary to the deposed shah.