KUWAIT CITY — Kuwaiti riot police on Sunday beat opposition protesters who were gathering for a massive demonstration against a decision to change the electoral law, organisers and witnesses said.

The clashes began as riot police prevented protesters from gathering at three different sites in Kuwait City and arrested several people including former Islamist MP Waleed al-Tabtabai, organisers said on their Twitter account.

Witnesses told AFP that riot police used smoke bombs to disperse crowds who began to gather at the three sites.

The organisers immediately changed the venue of the meeting to an alternative location in Kuwait City and urged protesters not to clash with police.

Organisers had expected the protest to be "the biggest procession in the history of Kuwait," and advised people to remain peaceful after a stern warning by authorities to prevent any "illegal" demonstration.

The demonstrators were scheduled to march on the Seif Palace which houses offices for the emir, crown prince and prime minister.

The interior ministry had cautioned that processions are illegal in Kuwait and that protesters can only gather in a square opposite the parliament building, warning it would deal harshly with violators.

Security in Kuwait City was beefed up as hundreds of unarmed policemen and dozens of police patrols were deployed, especially around the assembly points.

Police also cordoned off empty areas along the demonstration routes in an apparent bid to limit protester numbers by restricting parking, an AFP correspondent reported.

The protest was called by the Islamist and nationalist-led opposition in protest at a decision by Emir Sheikh Sabah al-Ahmad al-Sabah to amend the electoral law despite it having been confirmed by a court last month.

The emir on Sunday met bedouin tribal chiefs, and the official KUNA news agency cited many of them expressing support for Sheikh Sabah, although tribal areas make up the backbone of the opposition.

The opposition, which has decided to boycott polls called for December 1, said amending the electoral law amounted to a coup against the constitution and was aimed at manipulating the outcome to create a rubber-stamp parliament.

In the latest clampdown on opposition leaders and activists, the public prosecution service issued an arrest warrant for a member of the scrapped 2012 parliament, Osama al-Munawer.

Munawer joins three former opposition MPs who have been in detention since Thursday. The prosecution on Sunday extended their detention by 10 days, according to Al-Humaidi al-Subaie, one of their defence lawyers.

Four opposition activists arrested on Monday after clashes with riot police were also in custody.

Political tension has strongly impacted the Kuwait Stock Exchange which shed 3.05 percent at the start of the business week on Sunday, the biggest single day loss in more than three years.

The wrangling in the OPEC member has stalled development despite abundant oil-driven surpluses of more than $400 billion.