Christians in Scotland are urging First Minister Alex Salmond and Better Together leader Alistair Darling to join in prayer ahead of the referendum later this month.

A national day of prayer and fasting is to be held on September 17, 24 hours before Scots will go to the polls to vote on September 18. It is hoped that Salmond and Darling will each visit a church for a short time of prayer during that time.

Churches have also been encouraged to pray about independence on the previous Sunday.

"God's guidance is required for the proper functioning of society, in fact, for 300 years the Church has given spiritual guidance without taking sides," Fred Drummond, national director of Evangelical Alliance Scotland, said in a statement.

"While both sides focus on essential issues on the economy, society, family and environment, among others, God is the ultimate authority and we have a biblical responsibility to pray for our nation and its leaders at this crucial time.

"The Alliance and 15 other partner organisations and churches want church leaders in Scotland, and in fact right across the UK, to join us in prayer about what kind of nation we wish Scotland to be," he added.

"History has shown that prayer changes the course of history because God responds to the prayers of His people."

On September 17, churches across Scotland are therefore being encouraged to open between 7am and 10pm for people to come in and pray specifically for the future of the country.

At the turn of each hour, the Lord's prayer will be recited, and prayer offered particularly for "an outcome that benefits Christ's kingdom in Scotland."

Free Church of Scotland Moderator Rev David Miller said the Referendum will be "one of the biggest days for many years in the history of Scotland," making it all the more important to seek God's will.

"The referendum appears to be an opportunity to have a different country and a different future, but the wisdom and power to bring that about will not come from Holyrood or Westminster – which is why we do not wish to see a Scotland which is independent from God," he explained.

"The last thing we want is a secular state, whether called Scotland or Great Britain, in which God's laws are not worth obeying, in which His day is not worth valuing and in which His blessing is not worth considering."

Miller also insisted that the Church would continue to work alongside politicians both before and after the vote.