UPDATE 2-Tens of thousands of Kuwaitis march to urge voter boycott
* Opposition politicians not taking part in Saturday's election
* Protesters oppose changes to voting rules imposed by emir
* Government of U.S. ally urges Kuwaitis to vote, not protest
KUWAIT, Nov 30 (Reuters) - Tens of thousands of people marched in Kuwait on Friday calling for a voter boycott, a day before a parliamentary election that looks unlikely to defuse tensions in the U.S.-allied, oil-producing Gulf country.
Political activists and opposition politicians, who have already said they will not stand in the election, called the rally to protest at a decree that changed voting rules. They say it will skew the outcome in favour of pro-government candidates.
"The people want to bring down the decree!" demonstrators chanted, a spinoff from the main slogan in popular uprisings that have ousted four autocratic Arab rulers since early 2011.
But Kuwait's disaffected say they seek democratic reform, not revolution in the mould of Arab Spring revolts elsewhere. Kuwait's ruling emir said the amendments to voting rules were made to preserve national security and stability.
Marchers in the "Nation's Dignity" rally set off at 3 p.m. (1200 GMT) from various locations in Kuwait City, converged on the main, palm tree-lined coastal road and proceeded toward the landmark Kuwait Towers on the northeast side of the capital.
They waved balloons, national flags and banners, wore orange clothing - the colour representing the boycott - and sang songs. There was a light police presence and no sign of the armoured trucks and riot officers deployed against previous marches.
"This (voting rule) change is against our rights," 28-year-old social worker Abdul Mohsen said. "There is corruption in the government. We want to fight corruption."
Bader al-Bader, an unemployed 33-year-old said: "The government does not believe in having the real democracy that most people believe in nowadays. They believe Kuwait is just a big bag of money and an oil rig."
Kuwait has the most open political system among the Gulf Arab states and the government authorised Friday's march, hoping to see the opposition let off steam before the vote.
In dispute is the nature of political power. Parliament has legislative powers and the ability to question ministers. But the emir, head of the Al-Sabah family that has ruled Kuwait for 250 years, appoints the prime minister who chooses the cabinet.
The emir, Sheikh Sabah al-Ahmad al-Sabah, used emergency powers in October to cut the number of votes per citizen to one from four, saying the change would fix a flawed system and maintain security and stability.
The government says opposition lawmakers use parliament to settle scores rather than helping pass laws needed for economic development. Opposition politicians accuse the government of mismanagement and have called for an elected cabinet.
The Gulf Arab state has held four parliamentary elections since 2006, after a series of assemblies collapsed due to the power struggle between elected lawmakers and the government that has held up investment and economic reforms.
Opposition lawmakers won around two-thirds of the 50-seat National Assembly in February and formed a bloc that put pressure on the government, forcing two ministers from office.
In the past, candidates called on supporters to cast additional ballots for their allies. Supporters of that system say such informal affiliations are crucial in a country where political parties are banned.
"I am conscious that there are those who have called for a boycott of the election," Information Minister Sheikh Mohammad al-Mubarak al-Sabah said late on Thursday.
"I find this of great regret and I hope to the bottom of my heart that the 400,000-plus Kuwaitis who have the ability to cast their vote for their preferred candidate will exercise their democratic right to do so."
With opposition lawmakers opting out, the incoming parliament will include many political newcomers, and it remains to be seen whether the assembly will have a less confrontational relationship with the government than before.
A low turnout would undermine parliament's legitimacy in the eyes of many Kuwaitis and could aggravate tensions on the street, diplomats and analysts say.
"The emir changed the voting rules. We believe the change has to come with the parliament. It is the parliament that represents the people," said protester Hanouf, 40, a marketing specialist who declined to give her second name.
She said current election candidates were mostly new and unqualified with "no clue how to be in parliament or politics".
The opposition, a disparate collection of moderate Islamists, Salafis and populist politicians, dominated parliament until it was dissolved after a June court ruling.
The opposition has won the backing of youth groups who have already helped organise protests against the voting rule change.
Kuwaitis often hold protest rallies outside parliament. But recent marches in the streets beyond, which authorities said were unlicensed, were broken up by police using tear gas, smoke bombs and baton charges.