PHNOM PENH, Cambodia (AP) — About 20,000 Cambodian opposition supporters are wrapping up a three-day demonstration to petition foreign embassies and the U.N. for intervention in what they claim was a rigged election.

Opposition leaders leave Chinese embassy and begin long march back to protest park in Phnom Penh Friday. Pic: Kevin Doyle, @doyle_kevin, via Twitter.

The rallies, which end Friday, are the opposition’s latest push to demand an independent probe into the July 28 poll, which the opposition says returned Prime Minister Hun Sen to power illegitimately.

Throngs of cheering demonstrators marched through the capital this week as they delivered petitions to the French, British, U.S., Australian, Russian, Japanese, Indonesian and Chinese embassies and to the U.N. human rights office.

Official election results extended Hun Sen’s 28-year rule and gave his party 68 seats in parliament, compared with 55 for the opposition. The opposition says it was cheated out of a victory and is boycotting parliament.

* Some journalists attending the rally put the attendance at closer to 25,000: