A U.S. State Department team will visit Moscow this week to discuss the Syria crisis, a top official said Tuesday as Western pressure mounted on Russia to back new action against its Soviet-era ally.

"We are in the process of meeting (U.S. Secretary of State) Hillary Clinton's deputies who work on the Middle East and Syria in particular," Russia's Deputy Foreign Minister Mikhail Bogdanov told the RIA Novosti state news agency.

At least 16 gunmen have been killed in three days of fighting between Shiite Houthi rebels in north Yemen and Sunni Salafist extremists, according to claims by both sides on Tuesday.

"Four of our men were killed and six others wounded in confrontations on Saturday with Salafist gunmen in Al-Qobaaf," east of the Houthi stronghold of Saada, said Huthi spokesman Mohammed Abdulsalam.

The first trial of a senior official accused of killing demonstrators in the 2011 uprising against Libyan leader Moammar Gadhafi opened on Tuesday.

Former foreign intelligence chief Bouzid Dorda is accused of ordering security forces to "kill demonstrators and fire live ammunition at them" during the 2011 uprising that ended Gadhafi’s rule.

Two Jordanian Salafists have been arrested as they tried to cross the border into neighboring Syria to fight President Bashar Assad's forces, a security official and relatives said on Tuesday.

"Two men from the southern city of Maan were arrested Sunday on the border when they tried to illegally enter Syria," the security official told Agence France Presse.

Egyptians in their hundreds began gathering Tuesday in Cairo's iconic Tahrir Square ahead of a mass demonstration to protest against verdicts handed down in ex-president Hosni Mubarak's murder trial.

Hawkers selling tea, cakes or flags took up positions at the square in downtown Cairo, which was closed to traffic for the 1500 GMT demonstration called by Egyptian activists furious at the verdicts.

Israeli Prime Minister Benjamin Netanyahu said Tuesday that German-supplied submarines were "very important" for his country's defense, after a media report that Israel was fitting the vessels with nuclear warheads.

"Germany has underlined its commitment to Israel's security in particular with the sale of another submarine," Netanyahu told the daily Bild. "It is a very important addition to our national security."

When Sandra Tamari arrived at Israel's international airport, she received an unusual request: A security agent pushed a computer screen in front of her, connected to Gmail and told her to "log in."

The agent, suspecting Tamari was involved in pro-Palestinian activism, wanted to inspect her private email account for incriminating evidence. The 42-year-old American of Palestinian descent refused and was swiftly expelled from the country.

Regime forces went on the offensive against rebels on Tuesday, seizing a town in the central province of Hama, as at least seven people including an army colonel were killed in violence across Syria, monitors said.

After three days of bombardment, troops and pro-regime militiamen backed by tanks and armored cars entered Kfar Zita, the Syrian Observatory for Human Rights said, adding that rebel fighters had withdrawn.

Syrian government troops fought deadly battles with armed rebels on Monday as the European Union pushed for an end to a split with Russia over how to end the 15-month bloodshed.

In talks in Saint Petersburg with Russian President Vladimir Putin, EU President Herman Van Rompuy said the EU and Russia "might have some divergent assessments" of the situation in Syria.

The opposition Syrian National Council will meet at the weekend to replace Burhan Ghalioun who resigned as leader of the bloc late last month, SNC officials said on Monday.

The meeting will take place Saturday and Sunday in Istanbul, where a vote might be waived since there is a "consensus" candidate, the sources said on condition of anonymity.