Kuwaiti opposition leaders have vowed to step up pressure on the government in the wake of the resignation of Foreign Minister Sheikh Mohammad al-Sabah.

Opposition groups have called for a protest against Prime Minister Sheikh Nasser Mohammed al-Ahmad al-Sabah on Wednesday. They also say they want to question him concerning an alleged government corruption scandal.

On Tuesday, the official KUNA news agency said the foreign minister's resignation had been accepted. The news agency gave no reason for his departure, but the Kuwait Times quoted opposition lawmakers as saying it could be tied to a corruption probe involving alleged illegal money transfers.

Kuwait's parliament regularly challenges the government, which is dominated by the ruling al-Sabah family.

The prime minister has survived two no-confidence votes in parliament this year, the most recent taking place in June.