Iran had put off inspections scheduled for last week to protest a tough resolution by the watchdog International Atomic Energy Agency (IAEA) against Tehran for hiding sensitive parts of a weapons programme the United States claims is devoted to secretly developing nuclear arms.
"I was informed this morning by the Iranian authorities that the new date for inspectors' arrival in Iran would be on 27th of March, al-Baradai told reporters during a visit to Washington, where he is due to meet on Wednesday with US President George Bush.
"Although this delay is regrettable, nonetheless it is still within our time schedule for the conduct of investigations" in leading up to a meeting in June of the IAEA board of governors that is to rule on Iran's cooperation, al-Baradai said.
"I hope and trust there will be no further delays in respect to any future inspection in Iran. It is clearly in the interest of Iran to cooperate fully with the IAEA."
Al-Baradai said inspectors had intended to go to the Natanz plant in central Iran to verify that uranium enrichment there had been suspended as Tehran had promised.
He said the IAEA wanted "to make sure it is locked and that it is sealed, that it is not in operation."
Iran says its atomic programme
is for producing electricity
Iran strongly denies US accusations it is pursuing nuclear weapons and says its atomic programme is geared solely to producing electricity.
Al-Baradai told reporters over the weekend he and Bush, who made a major speech on non-proliferation in February, agreed on the need for tougher export controls on nuclear technology in the wake of reports of a Pakistani-run nuclear black market that supplied programmes in Iran, Libya and North Korea.
Both Bush and al-Baradai have said they want the IAEA to have a mandate for tougher inspections of national atomic programmes through an additional protocol to the nuclear Non-Proliferation Treaty (NPT).
Al-Baradai's visit follows an IAEA board of governors meeting in Vienna that passed a resolution condemning Iran for hiding sensitive nuclear activities.
Experts have said Iran could be developing the technology to make atomic weapons, even while honouring the NPT by claiming its nuclear programme is peaceful. Much of sensitive nuclear technology, such as enriching uranium, can have both civilian and military applications.
"I hope and trust there will be no further delays in respect to any future inspection in Iran. It is clearly in the interest of Iran to cooperate fully with the IAEA"
Head of IAEA
The IAEA said in a report issued last month Iran had failed to report possibly weapons-related atomic activities despite promising full disclosure.
Iran had not told the IAEA it had designs for sophisticated "P-2" centrifuges for enriching uranium nor that it had produced polonium-210, an element which could be used as a "neutron initiator (to start the chain reaction) in some designs of nuclear weapons," the report said.
This was despite Iran's claim last October it had given the IAEA a full picture of its nuclear programme.
Danger of nuclear fuel
Al-Baradai wants to eliminate the danger that nuclear fuel declared for peaceful uses could also be used to make atomic bombs by having a multilateral body make the fuel, rather than letting individual states do it.
The IAEA chief has said he and the US president will also discuss efforts to verify Iraq's alleged nuclear weapons programme as he feels the IAEA needs "at one point to go back and finish the job."
The IAEA had said before the war it did not think Iraq had nuclear weapons capabilities, despite the Bush administration's claim Iraq possessed weapons of mass destruction.
Al-Baradai was to meet on Monday US Senator Richard Lugar, head of the Senate Foreign Relations Committee and a champion of non-proliferation, who co-sponsored a law to help keep nuclear material from the former Soviet Union under secure control.