Syria holds a referendum today on a new constitution, dismissed by the opposition as a charade amid an intensifying crackdown on the revolt against President Bashar Al-Assad.

Forces loyal to Assad took the bombardment of rebel-held areas in Homs into a fourth week. Activists say hundreds of people have died in the violence in the central city.

"No one is going to vote. This was a constitution made to Bashar's tastes and meanwhile we are getting shelled and killed," said activist Omar, speaking by Skype from the rebel-held Baba Amro district of Homs.

"More than 40 people were killed today and you want us to vote in a referendum? ... No one is going to vote."

The International Committee of the Red Cross (ICRC) said it was still unable to evacuate distressed civilians from embattled Baba Amro. After a day of talks with Syrian authorities and opposition fighters, it said there were "no concrete results".

"We continue our negotiations, hoping that tomorrow (Sunday) we will able to enter Baba Amro to carry out our life-saving operations," said spokesman Hisham Hassan.

Conditions were nightmarish for some of those trapped by the fighting. "We have hundreds of wounded people crammed into houses. People die from blood loss. We just aren't capable of treating everyone," said activist Nader Husseini via Skype.

Assad has vowed to hold parliamentary elections within 90 days if the referendum approves the new constitution.

The new document would drop an article that makes Assad's Baath party the leader of state and society, allow for political pluralism and enact a presidential limit of two seven-year terms.

Activists leading the revolt against four decades of Assad family rule have called for a boycott of the referendum. In Damascus and suburbs where troops drove out insurgents last month, activists say they will try to hold protests near polling centres and burn copies of the new constitution.

State television showed video of officials stacking boxes of referendum ballots and preparing voting centres, and citizens interviewed said they planned to vote yes in the national interest.

Across the country, at least 72 people were killed in the conflict on Saturday, 24 of them in Homs, opposition groups said.

Four Western journalists, two of whom were wounded in a bombardment by government forces that killed two other foreign journalists on Wednesday, have yet to be extracted from shattered Baba Amro. It was unclear if they were specifically discussed in the ICRC talks.

The ICRC said its local partner, the Syrian Arab Red Crescent, had been able to carry out two evacuations in areas of Homs other than Baba Amro on Saturday.

But Husseini said people in Baba Amro were suspicious of the Syrian Arab Red Crescent and did not want to work with a group "under the control of the regime".

The ICRC said the Red Crescent was independent and its members were risking their lives to help those in need.

Turkish Foreign Minister Ahmet Davutoglu questioned how the vote could take place in the midst of such violence. "On one hand you say you are holding a referendum and on the other you are attacking with tank fire on civilian areas. You still think the people will go to a referendum the next day in the same city?" he asked at a news conference in Istanbul.

Davutoglu, whose country has turned strongly against its former friend since the Syrian revolt began in March, said Syria should accept an Arab League plan that calls on Assad to quit. - Reuters