The Global Fund to Fight AIDS, Tuberculosis and Malaria said Tuesday that $4 million meant to fight disease in Mali has been misappropriated, prompting them to halt three grants.

The announcement came two days after Malian Health Minister Oumar Ibrahima Toure resigned without explanation on Sunday.

The Global Fund said Tuesday that Malian officials have arrested 15 people suspected of committing fraud; those include several senior health ministry officials.

The international fund said in a statement Tuesday that two malaria grants would be temporarily suspended and a tuberculosis grant would be terminated. Together the grants are worth $22.6 million. The fund has approved some $128 million in assistance for Mali since its creation in 2002. This has come in the form of eight grants - six of them administered by the government.

"The Global Fund tolerates no fraud, and we take public action to stop it, recover lost money and establish new and trustworthy channels for resources so they can reach those in need," said Michel Kazatchkine, the fund's executive director.

Toure, the health minister, did not respond to requests for comment on Tuesday, nor did Malian government officials. But he had faced several public calls to step down over the Global Fund investigation, and Mali's president Amadou Toumani Toure vowed earlier to seek those responsible.

"Whenever someone is accused of wrongdoing, we will do what's needed so that justice is done," the president said Saturday. "We must not condemn people too quickly, however. It's my desire that everyone arrested in connection with this affair has the chance to defend themselves, protect themselves and possibly prove their innocence."

The fund said the $4 million appeared to have been skimmed through false invoices, fake bid documents and overcharging for goods and services.

The grants provided anti-malarial bed nets, malaria drugs and tuberculosis treatment for prisoners, people in mining communities and patients with multidrug resistant TB.

The fund says the malaria grants will be transferred to another recipient in Mali and treatment will not be interrupted. The tuberculosis patients helped by the other grant will also continue to receive assistance, the fund said.

The poor, landlocked West African nation relies on international donors to fund its health system. In August another international body, the GAVI Alliance, which helps get vaccines to developing countries, also froze the funds it gives to Mali because of corruption fears.