According to news reports and this official statement by LAN Airlines ( only in Spanish, sorry ), problems with the main provider of fuel ( COPEC ) are causing disruptions to their operations out of Santiago, for National and International flights.
They are using IQQ for fuel stop according to this statement.
Other airlines are also affected ( PAL and AA are mentioned by newspapers ), but obviously LAN is more affected due to the size of its operations from SCL.
There are no explanations for what problem COPEC had or when the fuel supply will be normalized.
The airline is preventing pax to check the flights before going to the airport.
[Edited 2011-12-14 06:28:21]