TEHRAN, Iran — Iranian President Mahmoud Ahmadinejad has fallen ill due to exhaustion brought on by his heavy workload, the state-run news agency reported quoting a close associate.

The announcement comes as doubts have surfaced over whether Ahmadinejad, who faces strong criticism from opponents, will seek re-election next year.

Parliament member Mohammad Ismail Kowsari, an ally of the president, said late Saturday that Ahmadinejad was feeling under the weather because of the strain of his position, according to the news agency, IRNA.

"The president will eventually get well and continue his job," said Kowsari, who accompanied Ahmadinejad last month to the U.N. General Assembly. "Every human being can face exhaustion under such a workload."

Ahmadinejad, who rarely misses meetings and public appearances, canceled a speech Wednesday at a conference and did not appear at a Cabinet meeting the same day. But the president, who turns 53 on Monday, did attend a religious ceremony on Saturday in Tehran, though he looked tired as he greeted supporters.

On Sunday, state TV also showed him receiving credentials of three foreign ambassadors.

Ahmadinejad, who is known for working long hours, has had low blood pressure and has gone to the hospital occasionally to seek treatment, said Mohammad Hossein Saffar Harandi, the Iranian Minister of Culture and Islamic Guidance.

"Even if you are immortal, you will suffer from working so much. ... That is what has happened several times to Mr. President over the last years. However, he is up and about and fresher than us right now," he told reporters Sunday.

In recent weeks, some supporters of Ahmadinejad have been discussing potential candidates for the June 2009 election, implying that the sitting president is not their automatic choice.

But Kowsari accused opponents of using Ahmadinejad's illness as an excuse to spread rumors about whether he will run for a second term.

"Those who use such a natural issue for psychological warfare will fail" to gain support in public opinion, he said. No other details about Ahmadinejad's illness were immediately available.

Since the 1979 Islamic revolution, every Iranian president has been re-elected to a second term, except the first one, Abolhasan Banisadr, who fled the country in 1981.

The months ahead are critical for Ahmadinejad if he wants to try to rebuild his political base and rebut critics who point to his unfulfilled campaign promises, including extending Iran's oil revenues to poorer provinces around the country. With more than 10 percent unemployment and 30 percent inflation, Iran was unable to bask in record-high oil prices earlier this year.

Ahmadinejad is also confronting questions about his uncompromising stance with the West over Iran's nuclear program, which has severely soured international relations. The U.N. has also placed three rounds of sanctions against Iran since Ahmadinejad took office in 2005 over Iran's refusal to halt uranium enrichment.