Turkey's President Abdullah Gül warned that the advent of modern communications meant people everywhere were far more aware of iniquities among nations.
"The wide gap between the countries is more visible today to people across the world," Gül said.
"It's also a big ethical and moral mistake, to have such a wide gap, and therefore unsustainable for political and security reasons," said Gül, whose own country provides $2 billion in aid to poor nations through official and non-government channels.
Addressing non-goverment organisations on Sunday, Ban cited some positives since the last conference in Brussels in 2001.
He said that in many LDCs more children were attending school, gender equality had improved, more women were earning and their representation in government had risen.
"Furthermore democratic elections are now the norm in the LDCs rather than the exception," Ban said.