TIMELINE: Political events in Iran in 2009

(Reuters) - Supporters of Iran's defeated presidential candidate Mirhossein Mousavi aim to keep up pressure with new protests on Wednesday over the disputed presidential poll won by incumbent Mahmoud Ahmadinejad.

Here is a timeline of the main political events in 2009:

January 20, 2009 - After three decades of mutual mistrust, new U.S. President Barack Obama offers a new beginning of engagement with Tehran if it "unclenches its fist."

February 19 - An IAEA report shows a significant increase in Iran's reported stockpile of low-enriched uranium to 1,010 kg, enough, some physicists say, for possible conversion into high-enriched uranium for one bomb.

March 12 - Obama says he is to extend sanctions against Iran as it continues to pose an "extraordinary threat" to the United States. On March 20, Obama issues a videotaped appeal to Iran offering a "new beginning" of diplomatic engagement.

-- Supreme Leader Ayatollah Ali Khamenei, a day after the videotape, says Obama's offer of better ties is just a "slogan," but pledges Tehran will respond to any real policy shift by Washington adding: "You change, our behavior will change."

April 22 - Iranian President Mahmoud Ahmadinejad accuses Israel of mass murder and ethnic cleansing against the Palestinians, two days after his denunciation of the Jewish state as racist prompted a walk-out from a U.N. meeting on race.

June 12 - Ahmadinejad wins the presidential election defeating challenger Mirhossein Mousavi. Thousands of people protesting against the election result clash with police. Mousavi calls result a "dangerous charade."

June 13 - More than 100 reformists from the leading reformist party Mosharekat are arrested.

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

June 15 - Seven people are killed on the fringes of 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 and many of them go to the state television IRIB building, which was ringed by riot police. Ahmadinejad's supporters mobilize thousands of demonstrators in central Tehran.

-- State television says the "main agents" in post-election unrest were arrested with explosives and guns.

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

Jun 17 - Saeed Laylaz, editor of business daily Sarmayeh, and pro-reform activist Mohammadreza Jalaiepour are arrested, a reformist source says.