"The government has reviewed the work visas of certain members of the... non-governmental organisations in view of the continuing police investigations into allegations of inappropriate behaviour," a government statement said.
The organisations concerned are the French and Spanish arms of Medecins Sans Frontieres (MSF, or Doctors Without Borders), and the French and US arms of Medecins du Monde (MDM, or Doctors of the World).
Sri Lanka's government has been at odds with foreign charities operating in the troubled northern and eastern regions amid an escalation of clashes between security forces and Tamil Tiger rebels.
Foreign organisations have often been accused of tacitly supporting Tamil Tigers, a charge they have vehemently denied.
The Peace Secretariat in Colombo -- which coordinates with peace broker Norway -- said that visas issued to the NGO staff members would remain valid until investigations were completed.
In August, 17 workers of a French charity, Action Against Hunger, w