Christians around the world are praying for Sudan at the start of a seven-day referendum to decide whether the country is to remain united or separate.

The long-awaited referendum marks the conclusion of the 2005 Comprehensive Peace Agreement that ended decades of bloody civil war between the predominantly North and the mainly Christian, oil-rich South.

Southern Sudanese are expected to vote for independence from the North, which they say treats them as second-class citizens.

In a statement on Friday, the Archbishop of Canterbury Dr Rowan Williams said January 9 was an “immensely important day for Sudan”.

He called upon people around the world to stand with the Sudanese people “to ensure that the referendum takes place peacefully and that the process and the results are fully respected”.

Church Mission Society is appealing to churches across the UK to set aside time on Sunday to pray for Sudan and the referendum.

Anglican churches in Salisbury and the Diocese of Connor in Ireland have put up prayer walls and resources on their websites to encourage people to pray for Sudan.

In Australia, Anglicans are also being urged to pray for a successful outcome.

Dr Julianne Stewart, Programs Director of the Anglican Board of Mission in Australia, who is scheduled to travel to Sudan later this month said, "We are asking all Anglicans in Australia to pray for peace in Sudan.Whatever the outcome of the referendum, our hope is that the millions of people who have suffered amidst the conflict of the past few decades will come to know lasting peace."

The World Evangelical Alliance has issued a call to its members worldwide to pray for a “free, fair and safe” referendum.

It is backing an urgent appeal from one of its member organisations, the Evangelical Fellowship of Canada, for prayer during and after the vote.

“While many seem confident that separation of the South will be the outcome of the January referendum, the hope for a peaceful acceptance by all parties seems much less probable,” the EFC said.

It has voiced particular concerns over President Omar al-Bashir’s promise to change the constitution in the North to Sharia law should the South vote to separate.

It warned that such a move could see an intensification of the persecution of Christians, who are already on the receiving end of discrimination in the North.

The EFC said: “Many are uneasy about what the constitutional changes in the North would mean to the already existing tensions between the North and South, and to the safety of Christians, particularly those living in the North.

“The potential of the new Sharia Law in the North, brings heightened and unsettling concern for the intensified persecution of Christians.”