Polling stations opened Sunday morning in the Central African Republican for a key referendum on a new constitution, which seeks to bring an end to deadly sectarian violence.

However, clashes in the predominantly Muslim district PK5 in the capital Bangui prevented voters from reaching polling stations.

At least five people were wounded, with two of them in critical condition, the AFP news agency reported, citing a Red Cross employee.

The PK5 district also witnessed unrest throughout the night, with UN peacekeeping sources saying gunfire erupted in the neighborhood before polling stations opened.

"It's since last night that these extremists have taken us hostage. They have distributed ammunitions to their elements to use all day Sunday to prevent the vote," said Muslim community leader of the PK5 neighborhood Ousmane Abakar, reported AP news agency.

Gunfire was also heard in the Gobongo district, known as a stronghold for the Christian "anti-balaka" militia, said a security source.

Around 11,000 UN, African Union and French peacekeepers are stationed in the country, although several territories are still under the control of militias and bandits.

'Stable future'?

If approved, the new constitution would replace the transitional charter, effectively limiting the presidency to two terms and introducing a senate as the primary legislative body.

It would also block members of the interim government from running in the legislative and presidential elections slated for December 27.

The landlocked African country has witnessed nearly one-third of its 4.7 million population displaced due to violence between Christian and Muslim militias.

In 2013, Seleka - a coalition of Muslim rebel groups - seized the capital and overthrew Francois Bozize, the country's Christian president, following a failed power-sharing deal. Nourredine Adam, a former rebel commander, said the vote should not go ahead.

The National Election Authority - the republic's official electoral body - sought to reassure voters over the referendum, despite issues with the distribution of voting cards and only 15,000 copies of the new constitution having been printed.

The UN hailed the referendum as a step forward for the conflict-stricken country, noting that it would provide the opportunity for a "stable future."

"The referendum is a significant milestone towards the end of the transition in the Central African Republic, which will lay new foundations for a stable future for the country and its people," said a spokesman for UN Secretary-General Ban Ki-moon.

The spokesman said that Ban urged "all national stakeholders to ensure that the referendum is conducted in a peaceful and credible manner," adding that the UN supports the transitional authorities.

ls/rc (AFP, AP, Reuters, dpa)