A planned Syria peace conference next month will only work if the government and rebels send credible negotiating teams, the U.N.'s deputy secretary-general Jan Eliasson said Tuesday.

"There have to be two, credible delegations to negotiate," Eliasson told reporters in Geneva, the planned venue of the talks.

Egyptian troops and policemen began sweeps of north Sinai on Tuesday ahead of a possible showdown with heavily armed gunmen who abducted seven security personnel, officials said.

A senior interior ministry official told Agence France Presse a "campaign has been going on for half an hour", while a policeman taking part in the operation told AFP that security forces traded fire with gunmen in a village in the restive peninsula.

Radical Salafist group Ansar al-Sharia, which Tunisian authorities have branded a terrorist organization, has called for a protest in the city of Kairouan on Friday against the arrest of its spokesman.

"Call to all Muslims to a protest in support of Ansar al-Sharia's spokesman Seifeddine Rais, in front of the headquarters of ruling Islamist party Ennahda near Bab Jalladine" in Kairouan, the group said on its Facebook page.

Saudi authorities have arrested 10 more suspects in an alleged Iranian spy ring unveiled two months ago, an interior ministry spokesman said on Tuesday.

The eight Saudis, a Lebanese and a Turk bring the number of people arrested to 28, the official SPA news agency quoted the spokesman as saying.

The U.N.'s children's agency warned Tuesday that up to 20,000 civilians, mainly women and children, could be trapped by harsh fighting in the Syrian town of Qusayr.

"The situation is desperate," UNICEF spokeswoman Marixie Mercado told reporters in Geneva.

The U.N. said Tuesday the number of Syrian refugees flooding into Jordan had suddenly fallen from several thousand a day to close to zero, warning that fighting may be blocking people in need from coming.

"In Jordan in the last four days, we have seen a significant drop in the number of (Syrian) refugees arriving," Panos Moumtzis, who heads the U.N. refugee agency's response to the Syria crisis, told reporters in Geneva.

The Syrian regime has put forward a list of five officials including Prime Minister Wael al-Halqi as potential negotiators in talks with the opposition, European diplomatic sources said on Tuesday.

The list, provided to Moscow in early March, also includes deputy prime minister Qadri Jamil and three other officials, the sources said.

Iran said Tuesday it is willing to attend an upcoming peace conference on Syria, arguing all influential parties must be included in the process for it to be a success.

"The condition for success in Geneva is that all countries with influence on events in Syria participate," foreign ministry spokesman Abbas Araqchi told reporters.

Saudi Arabia on Tuesday executed five Yemenis and displayed their bodies in public for killing a national and forming a gang that committed robberies across several towns in the kingdom, the interior ministry said.

The five were executed in the southwestern town of Jizan, bringing the number of people executed in the kingdom this year to 46, according to an Agence France Presse tally.

Violence in Iraq, including a bombing near a mosque, killed 18 people on Tuesday, officials said, the latest in a spate of unrest that has cost more than 370 lives so far this month.

The bomb near a mosque in Abu Ghraib, west of Baghdad, killed five people and wounded at least 16, officials said.