Former Kuwaiti premier Sheikh Nasser Mohammad al-Ahmad al-Sabah said Tuesday he was ready to face a probe over alleged coup plot and corruption that rocked the oil-rich Gulf state.

A senior member of the ruling family who left office in November 2011 after nearly six years in office, he and former parliament speaker Jassem al-Khorafi were accused in a lawsuit filed Monday of major corruption and of plotting a coup.

"Sheikh Nasser is prepared to answer all the points stated in a lawsuit with complete transparency and clarity," his lawyer, Emad al-Saif, said in a statement.

The suit was filed by Sheikh Ahmad Fahad al-Sabah, another senior ruling family member. The two sheikh's are cousins and nephews of the ruler.

Sheikh Nasser, 74, resigned from office after massive street protests over corruption charges that 13 MPs had received millions of dollars in bribes.

Khorafi, a wealthy businessman who was speaker between 1999 and 2011, made no comment Tuesday but categorically denied the allegations when the news first surfaced several months ago.

Prime Minister Sheikh Jaber Mubarak al-Sabah also filed a suit Monday asking the attorney general to investigate "allegations of money laundering, abuse of public funds and (financial) dealing with Israel," made by Sheikh Ahmad.

Sheikh Ahmad, a former energy and economy minister, claimed he has videotapes showing the two former senior officials plotting a coup and charged that they also stole tens of billions of dollars of public funds.

The government said in April the videotapes had been tampered with and were not authentic, but Sheikh Ahmad insists they are genuine.

The corruption allegations were also made by prominent opposition figures at a public rally last week.

Several opposition groups pressed demands Tuesday for an international investigation into the issue and reiterated calls for the resignation of the government and dissolution of parliament.

The Audit Bureau, the country's accounting watchdog, has been asked to launch a separate investigation into the allegations while the newly established Kuwait Anti-Corruption Authority said Monday it will start its work by investigating the case.