The government says the rally was unauthorised [EPA]

Twenty Kuwaiti opposition MPs have resolved to press ahead with plans to question the prime minister in parliament following a police crackdown at a public rally, which left several parliamentarians injured.

Medics and witnesses said at least five people were injured at the rally west of Kuwait City on Wednesday, while local media put the number of those hurt at 14, including four politicians.

Opposition MPs said they held Sheikh Nasser Mohammad al-Ahmad al-Sabah, the prime minister and a senior member of the Al-Sabah ruling family, responsible for the actions of the police.

Following a meeting of opposition politicians on Thursday, Jamaan al-Harbash, an MP, said: "We have decided to quiz the prime minister and the motion will be filed on Sunday."

The rally, which the government said was unauthorised, was the second in a series of opposition protests against an alleged "government plot" to amend the 1962 constitution, which made Kuwait the first Arab state in the Gulf to embrace parliamentary democracy.

The opposition MPs accuse the government and its supporters of trying to undermine the status of the constitution in a bid to suppress freedom and democracy.

Several opposition blocs in parliament have formed a loose group to defend the constitution.

Khaled al-Tahus, another MP, said the attack on the rally was "premeditated" and warned it will have "serious consequences on the government".

"The situation is too grave ... This only takes place in repressive countries ... The country is passing through a serious turning point," Tahus, a member of the nationalist Popular Action Bloc, said.

Independent MP Mubarak Al-Waalan called for the government to step down. "It's time for this government to go," he said.

Kuwait, OPEC's fifth-largest oil producer, has a 50-member parliament. The 16 cabinet ministers, of whom 15 are unelected, automatically become members of parliament and have similar voting rights as elected MPs.

The emirate has been rocked by a series of political crises over the past five years that led the ruler to dissolve parliament three times, while the cabinet has resigned five times.