I'm wary of putting a number on it because I've been so criticized for this. You're aware that the numbers vary between, on the government side, zero--and that's been up to about 7,000 now--and on the most extreme side,147,000. This is this figure that a Sri Lankan bishop mentioned of people missing in the war zone. You know that 40,000 is the UN panel number, and the report talked about possibly 70,000.
The only thing I can add to that is that the information I got that's worrying was leaked by an expatriate. It's World Bank population data from the mid 2010 for the northern areas. It's very detailed spreadsheets that look at every single village giving estimated returns and actual returns. From that, if you look at the population data--and this is Sri Lankan government data--and you compare it with.... It's data that was used for giving grants, so there is every reason to inflate it. But if you compare it with the previous numbers, before the end of the war, where people would also say the LTTE would want to inflate those numbers for rationed food...but if you compare the two, there's well over 100,000 people missing in that data. Most of them were from the Mullaitivu area, one of the areas devastated by the war, so the pattern of missing makes sense.
I'm not saying those people are all dead, but I have not seen any explanation for where they are. Some of them may have moved within the country. Some of them may have escaped to India, but I don't think you can account for tens of thousands of people.
I can't really be more precise than that.