The Council’s statement came a day after supreme leader Ayatollah Ali Khamenei’s turnabout call for an examination of opposition charges of vote-rigging.

The main opposition candidate, Mir Hussein Moussavi, and other opponents of the declared winner, President Mahmoud Ahmadinejad, however, rejected the recount concession. They demand that a new election be held.

With the threat of rising tensions a day after clashes left at least seven people dead — during the largest anti-government demonstration since the Iranian Revolution — the Iranian government cancelled all foreign press credentials and told Iranian journalists they could report only from their offices.

But news continued to flow out of Tehran. Meanwhile, Ahmadinejad appeared to try to project a secure grip on power, leaving Iran to fly to Russia on Tuesday for a meeting on international security.

Seeking to reclaim the initiative after the opposition’s enormous show of strength on Monday, Ahmadinejad’s supporters also called for their own rally on Tuesday, and demonstrators from both camps began to gather in the same part of Tehran. A spokesman for Moussavi was quoted as urging them not to attend “to protect their lives”, Reuters reported.

In Twitter feeds and on websites — a primary source of communication for the opposition — Moussavi’s supporters asked that protesters wear black in honour of the seven killed on Monday.

Speaking at Monday’s huge rally, Moussavi said he had written to the Guardian Council to complain about the election but had little hope of action from the panel because many of its members had supported Ahmadinejad ahead of the election.

“I believe annulling the election results would be the least harmful measure,” he said. “Otherwise people will no longer have confidence in the system and the government,” he said. But the Guardian Council rejected that demand, Reuters reported.

“Based on the law, the demand of those candidates for the cancellation of the vote, this cannot be considered,” Abbas Ali Kadkhodaei, a spokesman for the Guardian Council, told state television.