A Kuwaiti political group and two youth groups said Wednesday they solidly back calls for a constitutional monarchy as the wealthy Gulf state battles with a corruption scandal involving MPs.

A call for fundamental political reforms, including the appointment of a premier from outside the ruling family, was made on Sunday by the September 16 Youths group which plans to stage a major rally on Friday to press for change.

The fresh calls come as the public prosecution has launched an investigation into alleged huge illegal transfers into the bank accounts of at least nine MPs in the 50-member parliament.

According to local media and opposition lawmakers, accounts of a number of other MPs are likely to be probed over similar allegations. The amount of transfers was put at close to $100 million.

"The Ummah Party affirms the demands made by September 16 Youths are legal, constitutional and important to achieve real reforms," the Islamic party said in a statement.

The statement said that the constitutional monarchy, fully elected government, a law to legalise political parties and setting up an independent election commission "are necessary steps for the desired political reform."

These reforms can "take Kuwait out of its chronic political stalemate," said the party, which has the support of a number of MPs.

Youth groups Fifth Fence and Kafi, both representing independent youth activists, also backed the reforms and urged the resignation of the government and called for dissolving parliament and holding fresh elections.

The two groups urged their members to take part in Friday's rally.

"Kafi supports the proposed reforms ... (and believes) it is the real solution for our continued political crises," said the youth group in a statement obtained by AFP.

Under the proposed reforms, the Al-Sabah family which has been in power for more than 250 years, will still have the emir and crown prince as stipulated by the 1962 constitution.

Kuwait was the first Arab state in the Gulf to establish an elected legislature in 1962, and the 50-seat parliament enjoys considerable legislative and monitoring powers.

But the Al-Sabah family remains in control of most key cabinet posts, including the premiership and the so-called sovereign ministries of defence, interior and foreign affairs.

The Gulf state has been little impacted by the so-called Arab Spring revolution that has already toppled three leaders but opposition Islamist MP Waleed al-Tabtabai warned Kuwait could be affected.

"The breeze of Arab Spring is blowing on Kuwait but not to topple the regime, only to reform it," Tabtabai told a gathering Tuesday night.

The Gulf emirate has been rocked by a series of political disputes over the past five years, stalling development plans despite abundant financial surpluses amounting to $300 billion.