Arab League observers prepared Wednesday to visit three key protests hubs in Syria as world powers urged Damascus to give them full access as they try to seek the truth about a crackdown on dissent.
More bloodshed was also reported Wednesday in Syria, where army defectors killed at least four soldiers in the southern province of Daraa, the Syrian Observatory for Human Rights reported.
The monitors were due to visit Daraa -- cradle of more than nine months of anti-regime protests -- the northern flashpoint provinces of Hama and Idlib, and around Damascus to pursue their investigations.
"As of Wednesday evening, and from Thursday at dawn, the observers will deploy in Idlib and Hama and in Daraa," mission chief General Mohammed Ahmed Mustafa al-Dabi told AFP in a telephone interview.
Dabi, a veteran Sudanese military intelligence officer, said observers would also fan out 50-80 kilometres (30-50 miles) around the Syrian capital.
The observers arrived in Syria at the weekend and on Tuesday visited the flashpoint central city of Homs, which has been besieged by government troops for several months, according to activists.
Dabi said the visit to Homs had been "good", adding that he was heading back to the city on Wednesday and that more observers would join the mission which now numbers 66 monitors.
"We are going to Homs to take care of administrative issues with the revolutionaries," he said.
But activists charged that the army had pulled back heavy armour from the Homs flashpoint neighbourhood of Baba Amro ahead of Tuesday's visit by the monitors, accusing the regime of deception.
His comments came as Russian Foreign Minister Sergei Lavrov urged Syria to give the observers maximum freedom as they go about their mission in the violence-wracked country.
"We constantly work with the Syrian leadership calling on it to fully cooperate with observers from the Arab League and to create work conditions that are as comfortable and free as possible," Lavrov said Wednesday.
But the United States and Human Rights Watch warned Damascus was hindering the mission which started on the weekend following weeks of prevarication from Syria.
In a statement released late Tuesday, HRW accused the Syrian regime of hiding from the observers hundreds of detainees held in its crackdown on dissent.
"Syrian authorities have transferred perhaps hundreds of detainees to off-limits military sites to hide them from Arab League monitors now in the country," HRW said.
"The Arab League should insist on full access to all Syrian sites used for detention, consistent with its agreement with the Syrian government," the global watchdog said in a statement.
Washington also piled on the pressure, charging Syria had intensified attacks against its people ahead of the observer mission and urged the monitors to dig up the truth.
"We obviously look to these individuals to be intrepid in their search for the truth of what's happening on the ground," said State Department deputy spokesman Mark Toner.
He said the United States "would... demand that the Syrian authorities allow them full access to the Syrian people in order to carry out their mission."
"The regime used the last several days as an opportunity to escalate their attacks on several... neighborhoods in Homs and other cities prior to the deployment of these monitors," he added.
France has also warned Syria against attempts at concealment or manipulation.
On Tuesday, Syrian police used tear gas to disperse some 70,000 people who took to the streets of Homs as the observers visited, activists said, a day after dozens of people died in the city.
At the same time, some demonstrators were fired at with live ammunition as they made their way to the square, and four were wounded, one seriously.
The Britain-based Observatory said separate demonstrations were held elsewhere in the city, aimed at "exposing the ill practices and crimes of the regime."
Before joining the march on Al-Saa square, tens of thousands staged a sit-in in Al-Khalidiyeh neighbourhood, according to the Observatory, which also reported demonstrations in Bab Dreib and Jub al-Jandali districts.
At least 34 civilians were reportedly killed in Homs' Baba Amro district on Monday.
There was more bloodshed Wednesday, said the Observatory which reported mutinous soldiers ambushed a convoy killing at least four regular army troops and wounding 12 in Daraa province.
The UN estimates more than 5,000 people have been killed in the crackdown since protests against President Bashar al-Assad's regime began in mid-March. The government blames the violence on "armed terrorist" groups.