Syrian voters head to the polls early on Sunday, to take part in a referendum on the country's new constitution.

Across the country, more than 14,000 voting centres are available for residents to cast their ballots.

One poll official says turnout is much higher than expected.

(SOUNDBITE) (Arabic) BASSAM HADDAD, CHIEF OF ONE POLLING CENTRE, SAYING:

"Since the early hours, voting is good. It is so much more than we expected. We can say it is 200 percent of what was expected at this time."

The new constitution would drop an article that places President Bashar al-Assad's Baath Party as the state leader.

This is meant to allow political pluralism and prevent the president from being in power for more than two seven-year terms.

But those fighting the four decades of Assad family rule have called for a boycott.

Some activists in Damascus and nearby suburbs have said they plan to hold protests near polling centres and will burn copies of the new constitution.

Authorities have held two referendums since Assad inherited power from his late father 12 years ago.

The first installed him as president with an official 97.29 percent 'yes' vote, and the second renewed his term seven years later in a similar landslide.

The government touted these referendums as clearly democratic, but dissidents say they were a sham.

With voting under way, security forces have continued their bombardment of Homs and other towns.

Human rights campaigners say at least 100 people were killed over the weekend.

Travis Brecher, Reuters