This paper describes the components of a robust and wide-coverage morphological analyser for Basque. The analyser is based on the two-level formalism and has been designed in an incremental way with three main modules: the standard analyser, the analyser of linguistic variants, and the analyser without lexicon which can recognize word-forms without having their lemmas in the lexicon. Using lexical transducers for our analyser we have improved both the performance of the different components of the system and the description itself. The analyser is a basic tool for current and future work on automatic processing of Basque and its first two applications are a commercial spelling corrector and a general purpose lemmatizer/tagger.