The Khaleej Times reports that the pontiff also called for large-scale investment for fighting killer diseases such as AIDS and malaria.
The pope made the plea for "the rapid, total and unconditional cancellation" of debt in a letter written in December to German Chancellor Angela Merkel, who responded two months later.
However, the two letters were only made public on Monday by the Vatican.
"I welcome the fact that the question of poverty, with specific reference to Africa, now appears on the agenda of the G8," wrote the German pontiff, ahead of the Group of Eight (G8) summit in Germany on 6-8 June.
"Indeed, it should be given the highest attention and priority, for the sake of poor and rich countries alike."
He wrote that the fact the German presidency of the G8 coincided with it also holding the rotating presidency of the 27-member European Union offered "a unique opportunity to tackle this issue".
And he called for "a substantial investment of resources for research and for the development of medicines to treat AIDS, tuberculosis, malaria and other tropical diseases".
The international community must also continue efforts for the reduction of the "legal and the illegal arms trade, the illegal trade of precious raw materials, and the flight of capital from poor countries", he wrote.
"While these challenges should be undertaken by all members of the international community, the G8 and the European Union should take the lead," the pope said.
For her part, Merkel, in her reply, outlined her priorities such as the economic development of the African continent, stronger international commitment, fighting AIDS and debt cancellation.
Pope calls on G8 summit to cancel debt for poorest (Khaleej Times, 26/4/07)
LINKS (not necessarily endorsed by Church Resources)
British Caritas targets hypocrisy of G8 leaders (CathNews, 2/6/03)
Pope wants G8 leaders to 'hear the cry of the poor' (CathNews, 17/7/01)
27 Apr 2007