The head of the Dutch wing of Medecins San Frontieres (MSF) has been charged with crimes against the Sudanese state over a report on rape in Darfur.
Foreman is charged with crimes against the state
Paul Foreman was arrested on Monday and later released on bail.
The state crime prosecutor said Mr Foreman had failed to hand over evidence on which the report was based. The charity says it is confidential.
Pro-government militia in Darfur are accused of mass rape and killings, but the government denies complicity.
The BBC's Martin Plaut, who recently travelled to Darfur, says the charges are part of a concerted drive by the Sudanese authorities to end western criticism of their behaviour in the region.
He says that many Sudanese believe western aid workers have given information on alleged human rights abuses in Darfur to the United Nations, which has passed a sealed list of 51 war crimes suspects to the International Criminal Court.
Our correspondent says that in March, aid workers were threatened over their reports of mass rape.
"He (Mr Foreman) is on bail and not allowed to leave the country, " MSF Holland spokesman Geoff Prescott told the BBC's Focus on Africa programme.
"He's been charged with crimes against the state by the government on the grounds that they didn't seem to have appreciated our report on rape in Darfur".
Mr Foreman had said "medical privilege" and patient confidentiality prevented him from handing over documents requested by the authorities.
Another reason for respecting the information, Mr Prescott explained, was because women "made pregnant as a result of rape outside wedlock can be arrested by the authorities" in Sudan.
He said the charity stood by its report, which he described as "accurate and truthful".
Sudan's state crime prosecutor said he had come to conclusion that the report was false.
Mr Foreman could face up to three years in prison if found guilty of falsifying the report.
It is not yet known when he will appear in court.
"We would like to reiterate that we think it's the people who perpetrate rape in Darfur who should be in court, not the people who are trying to bring medical assistance to the victims," Mr Prescott said.
The report - The Crushing Burden of Rape: Sexual Violence in Darfur - which came out in March, was based on the treatment of 500 women over a four-and-a-half month period in Darfur.
It details nearly 300 of these cases, with several written up as witness statements, Mr Foreman said.
Contrary to Islam
Rape is a sensitive subject for the Sudanese government.
The government had always maintained that, as it runs contrary to Islam, rape is not taking place on the scale that numerous United Nations and international agencies have claimed.
Jan Pronk, head of the United Nations in Sudan, said he deplored the arrest.
"That document was a non-political document only based on humanitarian concern of MSF which has done an excellent job of helping victims of rape," Mr Pronk told the BBC.
MSF says it has a significant presence in Darfur, with more than 300 international staff and 3,000 local staff treating some one million patients.
The UN says that about 180,000 people have died in the two-year conflict in Darfur, and more than two million driven from their homes.