TIMELINE: Iranian election and aftermath

(Reuters) - Here is a summary of the main developments in the aftermath of Iran's June 12 presidential election, which took place against a background of tension with the West over Tehran's nuclear program.

June 13 - Hardline incumbent Mahmoud Ahmadinejad officially wins presidential election with nearly 63 percent of the vote compared with 34 percent for reformist challenger Mirhossein Mousavi, authorities say. Thousands of protesters clash with police. Mousavi calls result a "dangerous charade".

June 14 - Mousavi says he has formally asked Iran's Guardian Council to annul the election.

June 15 - Seven people are killed during a huge march by Mousavi supporters in central Tehran, state media says. There are also pro-Mousavi demonstrations in the cities of Rasht, Orumiyeh, Zahedan and Tabriz.

June 16 - Leading Iranian reformist Mohammad Ali Abtahi, a former vice-president, is arrested, his office says.

-- The Guardian Council says it is ready to carry out a partial recount of ballots but rules out annulling the poll.

-- Tens of thousands of pro-Mousavi demonstrators march in northern Tehran. Ahmadinejad's supporters mobilize thousands of demonstrators in central Tehran.

-- Authorities ban foreign journalists from leaving their offices to cover street protests.

June 17 - Thousands march in central Tehran.

-- Ahmadinejad defends the legitimacy of the vote, telling a cabinet meeting it has "posed a great challenge to the West's democracy," Mehr news agency reports.

-- Saeed Laylaz, editor of business daily Sarmayeh, and pro-reform activist Mohammadreza Jalaiepour are arrested, a reformist source says.

June 18 - Thousands of Mousavi's backers rally in Tehran to mourn those killed in the mass protests.

-- A spokesman for the Guardian Council says it has begun examining 646 complaints submitted after the June 12 vote.

-- Iran's English-language state television has reported eight people killed in five days of protests. The ISNA news agency, quoting provincial officials, says 88 people were arrested in post-election unrest in the city of Mashhad and up to 60 people in Tabriz in the northwest.

June 19 -- Supreme Leader Ayatollah Ali Khamenei says protest leaders would be responsible for any bloodshed if rallies continued against the election, which he said Ahmadinejad had won fairly by 11 million votes.

June 20 -- The Guardian Council says it is ready to recount a tenth of the votes in the disputed election.