  Multilingual sentence representations are the foundation for similarity-based
bitext mining, which is crucial for scaling multilingual neural machine
translation (NMT) system to more languages. In this paper, we introduce MuSR: a
one-for-all Multilingual Sentence Representation model that supports more than
220 languages. Leveraging billions of English-centric parallel corpora, we
train a multilingual Transformer encoder, coupled with an auxiliary Transformer
decoder, by adopting a multilingual NMT framework with CrossConST, a
cross-lingual consistency regularization technique proposed in Gao et al.
(2023). Experimental results on multilingual similarity search and bitext
mining tasks show the effectiveness of our approach. Specifically, MuSR
achieves superior performance over LASER3 (Heffernan et al., 2022) which
consists of 148 independent multilingual sentence encoders.
