* Activists calling for new parliamentary elections
* Numbers at marches have fallen since Dec. 1 vote
* Election boycotted by opposition after rules change
KUWAIT, Jan 22 (Reuters) - Kuwaiti police used smoke and stun grenades to scatter hundreds of protesters outside the capital on Tuesday after they gathered to demand the dissolution of parliament and fresh elections, witnesses said.
An initial demonstration, part of a series of marches against what activists regard as a rubber-stamp parliament, took place in the east of the oil-producing Gulf Arab state without intervention by police.
But security forces later broke up a group of protesters who tried to march towards a highway, witnesses said.
Kuwait bans public gatherings of more than 20 people without a permit and demonstrations outside pre-assigned areas are often forcibly routed by police citing security reasons.
Protest marches have occurred more frequently in the U.S.-allied country since the ruling emir, Sheikh Sabah al-Ahmad al-Sabah, used emergency powers in October to change the electoral system. He said the amendments were aimed at fixing a flawed voting system and would ensure political stability.
Opposition politicians, who include tribal figures and Islamists, say the new voting system was tailored to usher in a government-friendly parliament, and they boycotted elections on Dec. 1 in protest.
A demonstration on the eve of the parliamentary vote calling for a boycott drew tens of thousands of Kuwaitis, in what organisers described as the largest march in the country's history. Since the election, the number of protesters taking part in marches organised through social media has dwindled.
A long-running power struggle between members of the elected parliament and a cabinet, appointed by a prime minister chosen by the emir, has held up reforms, stalled investment and prompted the dissolution of a series of assemblies.
Kuwait has the most open political system in the Gulf Arab region and a parliament with legislative powers that can question government ministers over policy.
However political parties are banned and the al-Sabah family, which has ruled Kuwait for more than 250 years, retains the main levers of power. Top portfolios such as the interior, defence and foreign ministries are held by al-Sabah relatives.
(Reporting by Mahmoud Harby; Writing by Sylvia Westall; Editing by Mark Heinrich)