Medecins Sans Frontieres (MSF) also expressed concern saying malaria and dengue fever are expected to pose serious health threats to survivors in Indonesia's Aceh.
MSF said in a statement that a charter plane from Belgium to the Sumatran city of Medan, just south of Aceh province, was to bring 32 tonnes of medical and sanitation materials to the area.
"Hopefully, it will arrive tomorrow," an MSF statement said, adding that a second charter was to follow a day later.
Indonesia toll rises
Indonesia and particularly Aceh province suffered about half of the 56,000 people killed across Asia after Sunday's massive earthquake and the tidal waves it triggered, officials said.
Great tracts of land remained under surging tides on the northwest tip of Sumatra island on Tuesday and there was still no contact with many parts of the worst-affected areas.
"Air assessment of Aceh with helicopters is planned for tomorrow," MSF said.
"Malaria and dengue fever are anticipated to be serious problems. The desalination of water supplies will have to be a priority because salt water is contaminating fresh water supplies."
The agency said it was also dispatching "multiple teams" with drugs, water and other relief supplies to Sri Lanka which, it said, seems to be one of the most devastated countries.
MSF said it was also assessing the situation in Myanmar, Malaysia, Thailand and India, all of which were hit by the tsunami.
The disaster has led to the world's biggest-ever aid operation involving international organisations, neighbouring Asian states, European countries, the United States and countless people offering whatever individual help they can.