A new biography on former President Ronald Reagan has suggested that he once tried to convert Soviet leader Mikhail Gorbachev to Christianity.

“The Rebellion of Ronald Reagan” includes information from recently declassified documents and details a conversation between the former leaders of the USA and USSR during which Reagan apparently tried to convince Gorbachev that God existed.

Regan once said that he believed Gorbachev to be a “closet Christian” after he used the phrase “God bless”, although advisers said the expression was an idiom rather than an expression of faith.

The new biography tells of the leaders final summit meeting in Moscow in 1988. During the summit Reagan told the story of a World War II Russian soldier who turned to God just before dying of his wounds, despite being raise as an atheist in Soviet Russia.

Gorbachev had already told the President that he had been baptised as a Russian Orthodox by his mother, but added that he himself had no faith.

A presidential aid at the meeting noted that the President told Gorbachev wished to convert his son, who was also an atheist.

A declassified set of minutes of the meeting said, “The president concluded that there was one thing he had long yearned to do for his atheist son. He wanted to serve his son the perfect gourmet dinner, to have him enjoy the meal, and then to ask him if he believed there was a cook."

Reagan, however, swore the minute-takers to secrecy due to the potential for political embarrassment should the conversation be leaked.

Rudolf Perina was one of those recording the conversation. In the biography he is quoted as saying that Regan tried to convert Gorbachev, "Reagan thought he could convert Gorbachev or make him see the light."

A second assistant, Thomas Simons, said he believed the conversation reflected Reagan’s desire to avoid talking about other issues with Gorbachev.

Last year, there was speculation that Gorbachev may well be a believer after he was spotted kneeling at a shrine of St Francis of Assisi for 30 minutes. He said, "St Francis is, for me, the alter Christus, the other Christ. His story fascinates me and has played a fundamental role in my life."

Two months later the ex-Soviet leader contradicted his earlier statement, saying, "I have deep respect for believers. But I am personally an atheist."