Tunisian President Moncef Marzouki on Wednesday said his country would support an Arab peacekeeping force in Syria, as nations struggle to find a solution to the conflict.

"A peacekeeping operation by Arab nations is something we could well imagine," Marzouki told Agence France Presse on the sidelines of a U.N. General Assembly.

Six people were killed and 16 others wounded as a hand grenade exploded by accident in a local market of southern Yemen on Wednesday, a security official and a witness said.

The grenade exploded in Rabat market, in the Lahj province town of Rasd, killing six, including the person carrying it, the official said, requesting anonymity. "The incident did not have any political motivation."

Tunisian civil society groups expressed outrage on Wednesday after a young woman was accused of indecency by two policemen jailed for raping her, amid criticism of the Islamist-led government for rolling back women's rights.

The woman and her fiance were summoned by a magistrate on Wednesday to face the two policemen, both found guilty of rape and jailed, who accuse her of "indecency" and "assault," a group of Tunisian NGOs said in a statement.

More than 30,000 people, most of them civilians, have been killed in violence since the outbreak of a revolt against President Bashar Assad in March last year, a monitoring group said on Wednesday.

"At least 21,534 civilians, 7,322 soldiers and 1,168 defectors have been killed in the past 18 months," Syrian Observatory for Human Rights director Rami Abdel Rahman told AFP.

A Syrian rebel commander has accused the West of being complicit in the "unprecedented massacres" committed by President Bashar Assad's forces by refusing to arm the rebels with anti-aircraft weapons.

Rebel officer Ahmed al-Fajj, a brigadier-general in the regular Syrian army before his defection "in the first days of the revolution," spoke in the rebel Free Syrian Army-held village of Atmeh on the Turkish border.

Yemeni President Abdrabuh Mansour Hadi said late on Tuesday that he is ready for dialogue with militants of al-Qaida, but only if they give up their weapons and show repentance.

"I've always said that despite the blood that has been shed, the homes that have been destroyed and the people that have been displaced, we would consider dialogue on condition that they give up their weapons, announce their repentance... and stop protecting armed groups," Hadi said in a televised address.

Pro-government militiamen executed at least 16 civilians in their homes in Damascus before dawn on Wednesday, the Syrian Observatory for Human Rights said.

"Militiamen burst into their homes in the Barzeh neighborhood at 5 a.m. (02:00 GMT) and shot them dead," Observatory chief Rami Abdel Rahman told Agence France Presse.

Bombings and shootings mainly targeting Iraqi security forces killed eight people on Wednesday, among them a senior police officer, security and medical officials said.

The violence comes a day after a wave of attacks against members of the security forces left nine police and soldiers dead and 11 wounded.

U.S. Secretary of State Hillary Clinton's pointman for Syria, Fred Hof, is stepping down at a crucial time as world powers seek to end the conflict in the Arab nation.

"I can confirm that he is going to be retiring," a senior State Department official said late Tuesday.

Two suicide bombs struck the heavily guarded Syrian army headquarters in the heart of Damascus on Wednesday, killing four guards and sparking a gunbattle between troops and rebels, state media said.

A rebel officer and a rights group said the audacious attack which also left 14 people wounded was an inside job, while an Islamist rebel group said five of its fighters including a suicide bomber died in carrying out the assault.