DAMASCUS - Syrians go to the polls on Sunday for a referendum on a new draft constitution, as Damascus struggles under mounting international pressure to carry out reforms and end the country's turmoils.

A presidential decree issued on February 15 called a referendum for Sunday. There are about 14.6 million eligible voters, roughly two-thirds of the total population, and some 14,000 polling stations across the country, authorities say.

Voters will cast their ballots on the draft constitution that contains a bundle of reforms promised by the government.

The new draft constitution stipulates that power is practiced democratically through voting, whereas the current constitution states that the Arab Socialist Ba'ath Party is the leader of the state.

The draft constitution also says the president is directly elected by the people for a maximum of two seven-year terms.

A central committee that includes the Syrian interior minister and his two deputies will oversee the referendum.

Despite containing substantial reform measures, the draft constitution has received a cold shoulder from the opposition.

Hassan Abdel Azim, general coordinator of the Syrian National Coordination Body for Democratic Change, said the group, made up of 15 opposition parties, will "not take part in the referendum of the draft constitution, nor will participate in future elections."

The security situation at home has further worsened in the run-up to the referendum. Government forces have exchanged fire with militants in rural areas of Homs and Idlib provinces, resulting in casualties on both sides.

In the most appalling episode of recent violence, two foreign journalists, US reporter Marie Colvin and French photographer Remi Ochlik, were killed in a shelling of a media center in Homs city on Wednesday.

Some 70 representatives of foreign governments and international bodies gathered in Tunisia on Friday for a so-called Friends of Syria meeting, increasing pressure on Syrian President Bashar al-Assad to step down.

Participants, while divided on such issues as whether to initiate military action, reached an agreement in the end to turn up a notch of sanctions and isolation toward the Assad government and forge closer ties with the Syrian National Council, an opposition group which they recognize as one but not the only legitimate representative of the Syrian people.

US President Barack Obama also voiced his sharpest criticism to date Friday, saying he will maintain pressure on Assad and the United States and its allies will use "every tool available" to end the bloodshed.

Syrian authorities, meanwhile, condemned the Friends of Syria meeting, calling it a plot by "the enemies of Syria."

"Syria also totally rejects any calls to arm the opposition, as we consider it a move of support to terrorists that would hurt the Syrian people and their hope for peace and stability," an unnamed government source was quoted by the official news agency SANA as saying.

In the latest effort from the United Nations (UN) since the adoption of a resolution by its General Assembly that called on the Syrian government to cease violence, UN Secretary-General Ban Ki-moon on Thursday appointed Kofi Annan, former UN chief, as a joint UN-Arab League envoy on the Syrian crisis to broker a peaceful solution to the conflict.