Kuwaiti voters have elected pro-government candidates to replace five opposition MPs, who resigned two months ago, in by-elections that saw one of the lowest turnouts in the nation's history.

The results will boost the grip of the government on the 50-seat parliament where it already enjoyed a comfortable majority.

Almost all opposition groups boycotted the by-elections as they did during the general elections in February and December of 2012 that were both overturned by court judgements.

Authorities did not provide an official turnout figure but numbers posted on the information ministry website suggested it was around 23 per cent.

Three of the five winners were former MPs, according to results announced yesterday. The Shi'ite minority community increased its representation from seven to eight seats.

The by-elections were called after opposition MPs Riyadh Al Adasani, Abdulkarim Al Kundari and Hussein Al Mutairi quit two months ago when parliament rejected their request to question Prime Minister Shaikh Jaber Mubarak Al Sabah, a senior member of the ruling family, over allegations he gave cash handouts to MPs.

A few days later, Ali Al Rashed, a former speaker, and Safa Al Hashem, the only female MP, also resigned.

There are now no female MPs as all five women who stood in the by-elections lost. The by-elections were held amid a new political crisis over allegations that two former senior officials plotted a coup and were engaged in a major corruption scam.

The high-profile case, involving senior members of the ruling family, prompted Amir Shaikh Sabah Al Ahmad Al Sabah to appeal for calm in a televised address on Wednesday. The ruler urged Kuwaitis to allow the judiciary to handle the issue.

Between mid-2006 and last year, parliament was dissolved six times and there were more than a dozen governments.

The Amir has told his people not to threaten stability by playing "games" with politics, pointing to turmoil in neighbouring Iraq and elsewhere as examples of the dangers of political division.

"We do not have this luxury of differences and divisions and empty arguments and political games while catastrophes are right at our doorstep," Shaikh Sabah said in the address. "Are you aware of what is going on not far from us?" he asked.

He did not mention any country, but his comments appeared to refer to former occupier Iraq, which has been plunged deeper into turmoil by the sudden capture of much of its northern region by insurgents of the Islamic State of Iraq and the Levant (ISIL) .

The Amir urged Kuwaitis not to publicly discuss an investigation into reports of a recording of people discussing an alleged plot against the governing system in the country, saying the matter was being dealt with by the courts.

Kuwait's public prosecutor opened a case in December after a legal complaint which demanded an investigation into tweets about the alleged recording. Official media have said the alleged tape implicates unnamed people in an alleged plot "to overthrow the ruling system and challenge the rights and authority of His Highness the Amir".

Social media have been full of comments, with some suggesting that the case could damage relations inside the ruling family.-Reuters