Q+A: What next in Iran's post-election turmoil?

(Reuters) - More cracks have emerged among Iran's conservatives with renewed opposition clamor over a disputed June 12 election. Both sides are mauling hardline President Mahmoud Ahmadinejad on the eve of his second term.

The issue of detainees seized in post-election unrest has forced its way up the agenda since the death in prison last week of the son of a senior adviser to Mohsen Rezaie, a defeated conservative candidate and former Revolutionary Guard commander.

Mohsen Ruholamin's death has provided fresh emotional tinder for what is already Iran's worst internal conflict for 30 years.

Here are some questions and answers on what direction the political storm might take and the challenges it poses to Ahmadinejad and Iran's Supreme Leader Ayatollah Ali Khamenei.

WHAT CAN THE OPPOSITION DO?

Defeated presidential candidates Mirhossein Mousavi and Mehdi Karoubi, backed by reformist former President Mohammad Khatami, still proclaim the vote was rigged, defying Khamenei, who has endorsed the result and demanded an end to protests.

Mousavi and Karoubi have asked the Interior Ministry to authorize a silent ceremony in Tehran on Thursday to commemorate those killed in the unrest. No permission has been granted.

Opposition leaders have stepped up pressure for the release of at least 250 people, including prominent reformists, journalists, academics and lawyers, who are still in custody.

Mousavi, a moderate who was prime minister in the 1980s and who emerged as Ahmadinejad's main election challenger, has vowed to set up a new political front to "preserve people's votes".

Karoubi has proposed what would be an unprecedented popular referendum on the legitimacy of the government.

HOW HAS THE GOVERNMENT RESPONDED?

The government has accused its critics of inciting "riots" on behalf of Iran's Western enemies and blamed them for post-election bloodshed in which it says 20 people were killed. Reformists and rights groups put the death toll much higher.

Some hardline clerics have demanded that Mousavi and Karoubi be tried on charges that could carry the death penalty.

Khamenei, having rejected calls for the election result to be annulled or re-examined, is expected to confirm Ahmadinejad as president soon. Parliament will then swear him in.

This week the authorities have taken some steps to defuse tension over the detainee issue, perhaps reflecting concern among some senior officials about reports of harsh treatment.

Khamenei has ordered the closure of one Tehran detention center. The judiciary, ordered by its chief on Monday to review the cases of detainees, said on Wednesday that a disabled reformist, Saeed Hajjarian, would be released.

The head of a parliamentary committee set up to examine the issue said 200 detainees still held were street protesters and 50 were political figures, on whom verdicts were awaited.

IS KHAMENEI IN FULL CONTROL?

The supreme leader has the last word on affairs of state in Iran's blend of clerical rule and republican institutions.

But Khamenei's Friday prayer sermon on June 19 failed to silence Mousavi and others who said the election was a fraud and that Ahmadinejad's next government would be illegitimate.

The religious establishment itself is divided. Many senior Shi'ite clerics have refrained from congratulating Ahmadinejad.

Akbar Hashemi Rafsanjani, an influential former president and heavyweight of the 1979 Islamic Revolution, helped embolden the opposition in a July 17 sermon in which he said Iran was in crisis, demanding an end to detentions and press curbs.

Khamenei thus faces a rare challenge to his authority from senior politicians and clerical figures. So far he has made few concessions to the opposition. Nor has he ordered even harsher repression, such as the arrest of its leaders.

HOW IS AHMADINEJAD FARING?

The fiery president is backed by hardline authorities and the elite Revolutionary Guard, with its Basij religious militia, but his support base elsewhere appears to have narrowed.

If confirmed, he will enter his second term on the back of a bitterly contested election whose outcome prompted hundreds of thousands of Iranians to take to the streets in protest.

The dissension may have tarnished Ahmadinejad's appeal even to his admirers abroad who share his hostility to the West. It has also dampened any prospect of dialogue with the United States to calm tensions over Iran's disputed nuclear program.

Surprisingly, Ahmadinejad has also incurred the wrath of hardliners enraged by his choice of Esfandiar Rahim Mashaie, who is related to him by marriage, as his first vice president.

Khamenei publicly forced Ahmadinejad to dismiss Mashaie, who was once quoted as saying Iran had no quarrel with Israelis, only their government. The president then named Mashaie to head his own office. Two hardliners left Ahmadinejad's outgoing cabinet over the affair -- the intelligence minister, sacked by the president, and the culture minister, who resigned. (Writing by Alistair Lyon; Editing by Samia Nakhoul)