Thousands of Kuwaitis demonstrated Tuesday after a court sentenced three former MPs to three years in jail for insulting the emir, in a ruling the opposition described as "political".

Falah al-Sawwagh, Khaled al-Tahus and Bader al-Dahum were convicted of undermining the status of Emir Sheikh Sabah al-Ahmad al-Sabah at a public rally on October 10, their lawyer Mohammad al-Jumia said.

Kuwait's lower court on Sunday sentenced an opposition youth activist to five years in jail "with immediate effect" for insulting the emir on Twitter, a rights group said.

"The court passed the maximum jail term against Mohammad Eid al-Ajmi for insulting the emir on Twitter," the director of the Kuwait Society for Human Rights, Mohammad al-Humaidi, told AFP.

Twitter's unmatched platform for public opinion is emboldening Gulf Arabs to exchange views on delicate issues in the deeply conservative region, despite strict censorship that controls old media.

The authorities have been attempting to limit the damage by handing out jail terms to some whose tweets have been deemed offensive in the Muslim states, including in Bahrain, Kuwait and Saudi Arabia.

President Michel Suleiman hoped on Thursday that the promises of the international community to help Lebanon meet the demands of Syrian refugees escaping the fighting in their country would be translated into deeds.

“We received signals that there is a certain support … But previous experiences haven't been very encouraging,” Suleiman told a delegation from the Association of Arab Newspaper Reporters in Lebanon.

International donors on Wednesday pledged more than the targeted $1.5 billion in aid for stricken Syrians, U.N. chief Ban Ki-moon said, warning of a "catastrophic" situation in the war-torn country.

"I am pleased to announce that pledges have exceeded the target... more than $1.5 billion have been pledged including the $184 million pledged by non-governmental organizations," Ban told a news conference in Kuwait.

President Michel Suleiman urged donors on Wednesday to provide Lebanon with $370 million assistance for refugees from Syria and called for countries to take in some of the displaced after ringing the alarm bell.

The government has approved a $370 million comprehensive plan for the refugees - $180 for Lebanese state institutions and $190 for international agencies, he told the International Humanitarian Pledging Conference for Syria held in Kuwait.

Iraq on Tuesday approved a deal with Kuwait regulating the use of a shared waterway through which most of Baghdad's oil exports flow, which Iraq had accused its neighbor of attempting to cut off.

Control of the Khor Abdullah waterway is one of several outstanding issues between Iraq and Kuwait remaining from now-executed dictator Saddam Hussein's August 1990 invasion of the emirate.

Non-governmental charity organizations, meeting Tuesday in Kuwait ahead of a major donors conference, pledged $182 million for Syrian civilians affected by the deadly conflict.

The announcement was made during the meeting hosted by the International Islamic Charitable Organization (IICO) of Kuwait, the official KUNA news agency reported.

Dozens of Kuwaiti activists staged an unprecedented protest Monday outside the courtroom where opposition leader and former MP Mussallam al-Barrak was being tried on charges of insulting the emir.

"Jail us in place of Mussallam al-Barrak," chanted the activists who were prevented entry into the small courtroom in the Palace of Justice in the heart of wait City.

Prime Minister Najib Miqati noted on Monday that he had not sensed any indication from any political power that they are not seeking to stage the parliamentary elections in June.

He said before a consular delegation: “Given the recent discussions, it appears that political powers are leaning towards adopting an electoral law based on proportional representation.”