In multilevel systems it is important to avoid unwanted indirect information flow from higher levels to lower levels, namely the so called “covert channels”. Initial studies of information flow analysis were performed by abstracting away from time and probability. It is already known that systems that are considered to be secure may turn out to be insecure when time or probability are considered. Recently, work has been done in order to consider also aspects either of time or of probability, but not both. In this paper we propose a general framework, based on Probabilistic Timed Automata, where both “probabilistic” and “timing covert channels” can be studied. We define a Non-Interference security property and a Non Deducibility on Composition security property, which allow expressing information flow in a timed and probabilistic setting, and we compare these properties with analogous properties defined in settings where either time or probability or none of them are taken into account. This permits a classification of the properties depending on their discerning power.