Philippe Douste-Blazy made the announcement at the headquarters of the African Union peacekeeping mission in Nyala where French General Marc Delauney told him that bandit activity was undermining efforts to stabilise the region wracked by civil war since February 2003.
"The next months will be important in showing if the extra personnel that the mission requires can lower insecurity and improve the political situation," Delauney, part of a European group advising the African Union, told the foreign minister.
The African Union ambassador in Darfur, Burkina Faso's Jean-Baptiste Natama, said the peacekeeping force would need to be increased from 4000 to 7000 by the end of August, but the union lacked the resources.
Refugee camp visit
France has funnelled 80 million euros to Darfur through the African Union.
Douste-Blazy later travelled by muddy tracks to the refugee camp of Kalma, which houses 100,000 people and is 13km long and five km wide.
A humanitarian worker at the Kalma camp, which houses various ethnic groups and was the scene of riots in May, said lawlessness was a greater problem than food supplies and health.
"The situation is very tense and the refugees can't go more than a kilometre from the camp without the risk of falling victim to robberies and rape, in the case of women, particularly by the Sudanese police," he said.