* Kuwaitis protest against new voting rules
* Security forces fire tear gas at protesters
* Opposition says new voting rules puts it at disadvantage
By Sylvia Westall and Ahmed Hagagy
KUWAIT, Nov 4 Kuwaiti security forces fired tear gas to disperse an unauthorised demonstration on Sunday by thousands of opposition supporters against new voting rules for parliamentary elections on Dec. 1.
OPEC member and U.S. ally Kuwait has so far avoided the mass pro-democracy unrest that has toppled rulers in four other Arab countries since last year, but tension has mounted this year in a long-running power struggle between parliament and the government which is dominated by the ruling Al-Sabah family.
Next month's elections will be the second in Kuwait this year after an opposition bloc of Islamists, liberals and tribal leaders won a majority in polls in February.
That parliament was effectively dissolved by a court ruling in June that reinstated a more pro-government assembly, but the old legislature was unable to meet due to a boycott by lawmakers leading to another dissolution and a call by the emir, Sheikh Sabah al-Ahmad al-Sabah, for snap elections to end the deadlock.
The emir then announced changes to the electoral law last month which some opposition politicians say are an attempt to give pro-government candidates an advantage in the polls.
Opposition leaders have said they will boycott the elections and have called for demonstrations.
Hundreds of police lined the route in central Kuwait City hours before the planned march on Sunday, raising fears of a repeat of clashes last month between police and thousands of demonstrators that ended with at least 30 people hospitalised.
"A COUP AGAINST THE CONSTITUTION"
The Information Ministry had cleared its car park on the orders from the National Guard, news service al-Rai said in an SMS alert, while a large shopping mall along the proposed march route closed early.
Protesters instead gathered on the side of a motorway away from the centre of town, but security forces moved in and fired tear gas to disperse the main crowd of around 2,000. Many more Kuwaitis joined the protest in their cars or on the fringes of the main protest, but exact numbers were difficult to judge.
"Our duty is to maintain internal security and public order and to deter lawlessness in all of its forms," Interior Minister Sheikh Ahmad al-Hamoud al-Sabah said on state news agency KUNA.
But opposition activists were undeterred.
"We will continue. The opposition no longer cares about government statements," said an activist who declined to be named.
The Kuwait stock index fell to its lowest level since July 2004 on Sunday, according to Reuters data.
Kuwait has one of the most open political systems in the Gulf with an elected parliament with legislative powers. However, the 83-year-old emir has the final say in state affairs and picks the prime minister, who in turn selects the cabinet, with most of the important portfolios held by members of ruling family.
Under Kuwait's constitution, parliament confirms governments, passes laws presented by the cabinet and oversees the performance of various ministries. Lawmakers also have the right to summon ministers for questioning over policies.
The current crisis was sparked when the emir used his powers to order amendments to the voting rules, saying they were necessary for national unity.
The opposition has called the changes - which allow voters to choose only one candidate per electoral district - "a coup against the constitution", saying the reform would prevent its candidates taking the majority they won in the last vote.