Former British Prime Minister Tony Blair issued a plea to an American clergyman not to go ahead with his plan to burn copies of the Koran on September 11.
Mr Blair added his voice to those of the White House, the Vatican, the commander of international forces in Afghanistan General David Petraeus and film star Angelina Jolie, who all urged pastor Terry Jones to call off his protest.
But the pastor, who leads a tiny Florida church, insisted he would stage "International Burn-a-Koran Day" on Saturday, despite receiving more than 100 death threats.
Sky News reported that Anjem Choudary, former leader of the banned Islamist organisation Islam4UK, is calling on radical Muslim groups around the world to burn American flags outside US embassies in retaliation.
The pastor's supporters have been mailing copies of the Islamic holy book - which Muslims believe should be treated with the utmost respect - to put on the bonfire at his Dove World Outreach Centre in Gainesville to mark the ninth anniversary of the 9/11 attacks.
Explaining his plan, Mr Jones said: "Instead of us backing down, maybe it's time to stand up. Maybe it's time to send a message to radical Islam that we will not tolerate their behaviour."
In a statement, Mr Blair - who founded a Faith Foundation after leaving office to promote understanding between the world's religions - said: "I deplore the act of burning the Koran.
"It is disrespectful, wrong and will be widely condemned by people of all faiths and none. In no way does this represent the view of any sensible person in the West or any other part of the world."
The former PM added: "Those who wish to cause religious conflict are small in number but often manage to dominate the headlines.
"You do not have to be a Muslim to share a sense of deep concern at such a disrespectful way to treat the Holy Book of Islam.
"Rather than burn the Koran, I would encourage people to read it."